We had it come up a fair bit when we were younger...and weren't the best at addressing the root causes of problems, shall we say. It can also be used as a sort-of in-game bullying. In every campaign now, I always rule that you cannot roll dice against another PC. Even if someone wants to do something like give the other character a wedgie, I always ask the player "do you let them." If they say no, it doesn't happen.
My general rule is that character individuality stops where it starts impacting the fun of the rest of the table. Characters need to be able to work together, and the players need to be able to trust the other players at the table. As the DM, I need to be able to trust the players at the table. And that includes trusting them to know the group's tolerance for in-character friction. When that starts breaking down, the inevitable result is the player causing the trouble either shapes up or they get the boot.
No amount of "I was just playing my character" can make it okay. Because if it gets to that point, it's the players (and possibly the DM) that are mad about it. D&D is designed as a group activity, and if your character can't play as part of the group, then that's a problem.