I've had worse things done to me. One time in a game a guy started shaking the table. I was wondering what was going on and then I looked and saw his hands on the table legs.
Offering draw during live in desperate positions

That sounds like an OTB experience though. I once almost got into a fist fight during a blitz team event. My opponent had held my queen firmly in his hand (after an exchange) when we reached a position where I could promote a pawn and time was extremely tight for both of us. I realized, however, that I could still do a controlled mate with a rook and took that instead of queen during promotion. My opponent, was convinced I had chosen a queen and when we reached a position which would have been stalemate with queen, but mate in one with rook, he claimed draw, which I denied and director ruled in my favor. He was so utterly convinced that I had been moving the rook as if it was a queen (normally what blitz players do is turning the rook on the head and use this structure as a substitute queen) that he thought I cheated on him and willfully lied to the tournament director. I swear, I never made queen moves, but I am sure he believed that I did in the hectic of the final moves. Anyway, in that moment he was so upset, that he reached over the board, and wanted to get physical. That was definitely the climax of that tournament and attracted a big crowd....
Here is a truly unfair tactic I have seen employed by a bunch of assholes. Once you are in a desperate position offer a draw with every move. This will get you definitely a point during bullet if your opponent plays on an iPad. I say: get a life if that's the best you can do. And here is the first player who does this: runbabyrun