Use the following trick when you have a teammate that is annoying you during a Hardcore match. First, make sure you do not have Stopping Power. Next, take your pistol and fire a shot into their legs. Chances are, if you make it look like you did it on purpose, they will kill you. This is fine, as you want them to kill you. When they kill you, it will show up on people's screen that that player just killed a teammate. Find the player and shoot them once again. They should again retaliate and kill you. Do this a third time, and the game will auto-kill them, and the rest of the people on your team will assume the player is a Team Killer, and may help you kill him. This should frustrate the player enough to make them leave the game, all without you being penalize.

If you are the host of a game, press PlayStation Logo to bring up the Cross Media Bar menu. Go to "Friends List", and find the "Players Met" menu. Look there for the player that is annoying you. Press Triangle on their name. Add them to your "Block List" and it should kick them from the game. If you are a host, players on your Block List are unable to play a game with you and are thus auto-booted from the game.