I’ve never done anything that dramatic. I’ve gotten a little grumpy at losing sometimes, but I’ve always tried to be polite about it to my opponents. I think the worst I’ve ever said or done was when someone said “Good game” to me after a particularly brutal loss, I responded with “for you” or something like that.
The worst behavior I’ve seen at a tournament was at the Miami Open this past September. There were a couple of incidents there.
In the first one, there were two guys playing at a table near me who got into a relatively quiet position with very few pieces and lots of pawns, all locked up across the board. It was looking pretty drawish, but I’m no expert (this was in the U1600 section, after all). So one guy offers a draw, and the other guy decides to play on. I think the first guy offered the draw a couple of times on subsequent moves, then started to get upset. He actually stands up at one point, and although he’s still trying to whisper in the tourney hall, he’s like “It’s a draw, dammit!” in a pretty loud whisper so everyone around heard him. Eventually, the other guy agreed, and they quit playing, but I thought that was pretty rude. When you enter a game with a time control, you agree to play for as long as the clock is running, or until a checkmate or forced draw. Your opponent has the right to play on, even if you think they should agree to a draw or resign, to get it over with.
In the final round of the Miami Open, there was a much worse incident. I think it was in the lowest section, but I was nowhere near that area, so I’m not entirely sure. There was an adult playing a kid and at one point, the adult got really upset at one of the spectators. There was real yelling this time, and it went on for several minutes. It sounded like he was accusing the guy watching of helping the kid who was playing. A TD came over and calmed things down, and the game ended shortly afterwards. Then there was more yelling, and the adult player had to be “escorted” out, but on the way out, it turned physically violent, with the TD having to break it up. I was still busy playing my game, so I didn’t catch all the details, but I heard the police were called.
Kinda makes the king throwing thing seem pretty tame by comparison, doesn’t it? 
–Fromper