I used to run official Pokemon tournaments (its all sanctioned and you get prizes and points to go to higher competitions) and this guy used to come, claimed he had women 'eating out of the palm of his hand' and constantly bragging shit about his sexual prowess in front of the younger kids we had attending league sessions and tournaments and that.
We had a new girl show up, which was kinda rare, she was real nice and real good at the game and all. Bragging guy was paired up against her in round 3 or whatever, she beat him easy, and he fucking exploded 'I DIDN'T GET BEAT BY A GIRL SHE CHEATED, FUCKING BITCH' I was getting in telling him to call down or he'd be getting disqualified, but he was going mad. She very gracefully agreed to redo the match to placate him, she beat him again, and he was fucking bouncing off the walls 'FUCKING SLIMY BITCH, SHE WAS FLASHING HER TITS AT ME DISTRACTING ME SHE SHOULD BE DISQUALIFIED' And in the end, he was disqualified and we never saw him again.
Thats top of my list.