Cried after losing the last round in a tournament. If I won could've got second. The opponent had 10 seconds left T_T depression.
I still remembered the tournament last year. It was the penultimate round, me and my teammate was paired against each other. That blitz game was very important for both of us, because both of us are 5/5. In the end, with a completely equal position (I had a reputation of drawing against him) he had 33 seconds left, and me 27. He blundered a very easy fork (about 1500 in chess.com puzzles) and he lost. He cried. I went on to win the tournament with a round to spare. (my friend was @dinhnhokiet or @greenbanana2010 if that interests you.)
I remember seeing a video about some large Canadian tournament (some championship I think) where the guy who won hid his opponent's queens and put them back when his opponent lost because his opponent used an upside down rook.
I saw that. It was so disgusting.