Was in a RP a long time ago where one of the members was always making his character the focus. If (looking at names above me) HollywoodMole's character is particularly well read then his character will start spouting quotes immediately. If UnseenShade's character was a member of a small military unit that had to use guerrilla tactics to survive for weeks in some horrid battle, well then as it turns out his character is the master of guerrilla warfare. He did that kind of thing several times, the GM warned him, the OOC warned him, I even sent him a few PMs because he seemed like a decent guy who just didn't realize what he was doing.

The GM ended up posting a very brief IC post wherein his character shot the other guy's character in the leg and then (with a line I'm pretty sure came straight from Boondock Saints) shot that character in the head and buried him.

It was sort of necessary at that point as he just wasn't getting it, but he was the second poster effectively kicked out of that RP and it left a bad taste in my mouth.