In the world of sports, there is in a sense, an unwritten code of honor and conduct. It's called sportsmanship. In essence, athletes are expected to behave like gentlemen (gentlewomen as well) before and after contests and maintain a level of mutual respect during.

Obviously there is nothing absolute about these unwritten codes because plenty of athletes pick and choose which to follow. Most athletes taunt or "chirp" and now accept trying to get under an opponent's skin as part of the game. Others, in contact leagues, go so far as to try to hurt other players intentionally. Head-hunting is still considered unsportsmanlike and likely always will be. These are just examples, but the list goes on.

As far as sportsmanship with regard to fans, there are also codes of conduct, but they are far more "unwritten" and in many cases, not followed at all. As a general rule, fans are not supposed to behave in such a way that diminishes the enjoyment of those nearby. Anyone who has ever gotten blind drunk at a sporting event, shouted threats or obscenities at opposing fans, or held a massive sign that blocked the view of those sitting behind has broken the rules, but who cares, right?

Probably the most frowned upon way a fan can contribute to a miserable game-day experience is by interfering with a contest. People show up at sports events to watch heroes and foes battle it out in an entertaining test of strength, agility and endurance, not to see some yahoo invade the field, rink or ring and cause havoc. Here are our fifteen most ridiculous and notable instances of fan interference.

15 15. Pete and Jerry Cusimano - The Detroit Octopus

Our first example of fan interference is the Detroit Red Wings and their tradition of octopus throwing. It is now a cherished part of any Red Wings playoff run but it started out as two fans chucking an octopus on the ice back in 1952. The Red Wings were looking dominant in that year and after sweeping the Toronto Maple Leafs in four games, they took on the Montreal Canadiens. They were up 3-0 over the Habs and were set for game four, at home, on April 15th, 1952. Brothers, and seafood store owners, Pete and Jerry Cusimano of Detroit hurled an octopus on the ice before the game; its eight limbs each symbolizing a victory needed to win the Stanley Cup. This was, of course, back in a time where two best of seven series were required to be won in order to hoist hockey's holy grail. Because this has become a tradition and has been emulated by other fan bases, it is relatively harmless, but still an entertaining piece of hockey history and fan interference.

14 14. 1908 Olympic Marathon - The Glass of Champagne 

Booze has gotten in the way of many an athletic career, but during the 1908 Olympics in London, it cost a marathon runner what should have been a victory. Charles Hefferon was born in England, raised in Canada but spent much of his adult life in South Africa and competed for that country in 1908. During the marathon event, he was leading until around mile 24. There are, of course, about 26 miles in a marathon and he was confident in his lead. Thus he accepted a drink of champagne while running along the route. Less than a mile later, he experienced a cramp, slowed down and ultimately lost to American Johnny Hayes.

Both the fan who offered the champagne and Hefferon are at fault here, but the runner more so for sure.

13 13. NFL Snowball Games 

The most recent of the snowball-influenced NFL games in the league's history is that between the New York Giants and the San Diego Chargers in 1995. Giants fans, around the end of a 5-11 season, pelted players and the field with snowballs, resulting in over 100 ejections and over a dozen arrests. Ultimately the Giants lost by ten.

The game in which a snowball turned the tide of the game, however, was ten years prior during a 1985 game between the Denver Broncos and San Francisco 49ers. The Broncos were up in the first half when the 49ers tried for a field goal, but a thrown snowball resulted in a mishandled snap and a failed attempt. The score would end up 17-16 for the Broncos.

12 12. Jeffrey Maier 

The first of (spoiler alert) three very similar events at baseball games, Jeffrey Maier was just twelve years old when his name became popular in New York and infamous elsewhere. Back in 1996, while attending a game during the American League Championship between the New York Yankees and Baltimore Orioles, Maier caught a Derek Jeter fly ball. The ball was well-hit and Maier reached over the wall, grabbing it while outfielder Tony Tarasco was trying to make a catch. Umpire Rich Garcia called it a home run, but many thought it should have been called fan interference.

The Yankees tied up the game with that call, and would later win in extra innings. They went on to win the series and the World Series four games to two over the Atlanta Braves.

11 11. Malice at the Palace 

This was probably the most intense fight in the history of the NBA. The scene was a home game for the Detroit Pistons and they were facing the Indiana Pacers back in 2004. While the Pacers were a solid team and made the finals the year before (losing to the San Antonio Spurs) they were having an off-night on November 19th. Down by fifteen with under a minute left, a fight broke out between Ron Artest (Metta World Peace) and Ben Wallace.

After things had calmed down somewhat, Artest went and laid down on the announcers' table, at which time a fan, John Green, threw a drink at him. He charged the stands and began attacking another fan. This resulted in multiple fans and players getting involved in a massive scrap that left several injured, resulted in legal consequences for players and some of the fans, along with bans for a couple of season ticket holders who were involved.

10 10. Michael O'Brien - The First Sporting Event Streaker 

While the "phenomenon" of streaking goes back further than the 1970s, 1974 is the first documented instance of a fan doing so at a match. It was a rugby match back in 1974 between France and England that was being played at Twickenham Stadium in London. As of 2006, when he finally gave an interview, he had become a successful businessman, but back in 1974 he had been bet by an acquaintance who had no idea that O'Brien was never a man to back down from such a wager.

Though he hasn't said he regrets the incident, he did admit that he did not care for the amount of stupid streaking attempts that happened after his. He argued that those who ran out in the middle of play or during racing events were a real problem, while his streak occurred during half-time.

9 9. James Miller - The Fan Man 

If James Miller had lived years later, worn a GoPro, and maybe, just maybe avoided sporting events, he might have been known as an awesome daredevil, like Jeb Corliss, rather than a nuisance. He flew into several sporting events in the early 1990s, but none was more notorious than his entrance into 1993's boxing title fight between Riddick Bowe and Evander Holyfield. Holyfield would eventually be named the winner in the bout, but round seven was interrupted by Miller flying in through the roof. His parachute strings became tangled in the lighting apparatus and he eventually tumbled into the crowd where he was beaten and lost consciousness.

He was taken to hospital and issued a fine, and the fight continued twenty minutes later. Miller had trouble getting employment and received death threats for some time after this event and a couple of other flying stunts that got him arrested. In 2002, at age 38, Miller hanged himself in the woods up in Alaska, where he had moved to escape his own infamy.

On a much lighter note, the stunt was parodied in an episode of The Simpsons in which a "Fan Man" character flew into a stadiumwhere Homer Simpson was going to fight Mike Tyson-based character, Drederick Tatum. Seeing Homer getting obliterated in the ring, his manager Moe Szyslak (the bartender) uses the motorized apparatus to save Homer and fly away.

8 8. Disco Demolition Night

Ahhh, Disco Demolition Night. The hilarious answer to the question "what happens when you let too many people into a baseball double header for cheap and feed them beer and treat them to a fireworks display?" Let's start at the beginning. It was Chicago, back in 1979. Disco music was on its way out and rock was dominant once again. A local radio personality, Steve Dahl, organized an event that would take place between two Chicago White Sox/Detroit Tigers games. Anyone who brought a disco record to the game would be admitted for 98 cents and those records were to be blown up between the two games.

They planned for about 20,000 in attendance but over twice that number showed up and when the explosion took place, fans (many of them FUBAR from beer consumption) rushed the field, throwing records around and throwing pieces of sod at each other. The White Sox forfeited the game.

7 7. UCLA VS Arizona - Fake Ref

We already discussed the first streaker in sports history, but this was a whole different ball game, pun intended...awesome. This was just a few years ago during an absolute massacre of a game when Arizona was beating UCLA 42-7 heading into the half. A fan dressed as a ref charged on the field and blew the play dead before running around the field removing his clothing.

After the young man was subdued, the real refs had a situation on their hands as both teams had cleared off the sidelines and were on the warpath. Nothing like a massive brawl to liven up a game that's 42-7 at the half.

6 6. Caleb Humphreys 

This is the most recent entry and goes back just a couple of months to when the Toronto Blue Jays and now MLB champs Kansas City Royals were duking it out in the ALCS. It was game six in Kansas City and, during the second inning, Mike Moustakis smacked one deep. 19 year old bearded Royals fan Caleb Humphreys reached to grab what he believed was a home run ball. Blue Jays and their fans contend that his glove was in the field of play but the play was called a home run. The Royals won the game and the series. Caleb Humphreys may have a slight celebrity status down in Kansas City but it may be safe to say he might have to use a fake name if he ever has to come to Canada.

5 5. Steaua Bucharest - Fan Attacks 

Soccer fans are a special kind of crazy. I don't mean this in a negative way, in fact, Europeans get into sports in a way that is ridiculous in comparison to almost everyone except Oakland Raiders fans. Back in 2011, during a game between two Romanian teams: Petrolul Ploiesti and Steaua Bucharest, a fan invaded the pitch and slugged defender George Galamaz in the face. Galamaz had to leave the game and was diagnosed with a broken zygomatic bone (cheek).

4 4. Stanford Marching Band 

This goes all the way back to 1982 and a close game between the University of California Golden Bears and Stanford Cardinal. With less than five seconds remaining in the game, Stanford had taken the lead, 20-19. John Elway was playing for Stanford at the time, for those who want to appreciate how long ago this was.

During the post-field goal kickoff, the Bears started to lateral the ball to one-another and one was nearly brought down (there are two parts of this play that are still hotly debated), but ultimately, Kevin Moen ended up with the ball and weaved his way through the Stanford band, who had wandered onto the field after it seemed a California player had been tackled.

With regard to this play, a couple of the laterals have been challenged as forward passes and it occurred more than once that a California player was tackled while getting rid of the ball and some consider those to have been potential ends to the play.

3 3. Boston Patriots Fan Blocks Game Winning Pass

If 1982 wasn't far enough in the past for you, this entry goes all the way back to 1961. The NFL didn't exist yet, the New England Patriots were the Boston Patriots, and Texas had a team called the Dallas Texans. The Patriots at the time were pretty much the laughing stock of the AFL and in a game against the Texans, a fan snuck out of the crowd and grazed a pass that would have potentially won the game for Dallas. They never caught the fan and the Patriots won the game. To his credit, his defense on the play was as impressive as his ability to get out of dodge without being tackled.

2 2. Steve Bartman

The first two baseball fans we saw so far, Caleb Humphreys and Jeffrey Maier, helped out their teams and were praised by their fellow hometown fans. Steve Bartman is the most notorious fan in baseball history because he is considered to have started the implosion of the Chicago Cubs back in the 2003 playoffs.

This play took place during the 2003 National League Championship Series. The Cubs were ahead three games to two in the series and winning late in game six. Bartman went to catch a foul ball while Moises Alou was also going for it. The ball went uncaught and the Cubs gave up eight runs that game and would go on to lose the series. Bartman had to be escorted home by security that night and his life has not been the same ever since. I don't want to go out on a limb here but it would seem that Chicago fans are passionate about their Cubs.

1 1. Monica Seles Stabbing

This is by far the most violent fan interference with a match and therefore we consider it number one for notoriety. Monica Seles was one of the biggest stars in the tennis world back in the early 1990s, winning eight major titles before she turned 20 years old. In 1993, however, her career was derailed when a German fan, Gunter Parche, who, as they say "had more issues than a news stand" stabbed her during a match. She was out of tennis for two years after this event. Parche was not charged with a criminal offense, due to his mental condition. She returned to tennis in 1995 but had less success than she experienced earlier in her career.