I just think it'd be sweet revenge to somehow lure him into your room to pull his usual prank, where you do the following: with the lights dimmed, in full cammo, in a "fortified" position (couch w/ pillow "sandbags" will make a nice foxhole), and with a rope in your hand that is attatched to a pulley/the door so you can close it behind him, you unleash all fury with
this airsoft gun. A practically solid stream of 800 pain-inducing bb's per minute with no immediate escape and no way to hit you back with his weapon will make him think twice about EVER assaulting your "base" with a springer (single shot) airsoft gun again. Granted, it could be the start of a war, but you'd have the upper hand.
I probably wouldn't do it for the price of the things and the liability involved. Still, tell me that doesn't at least sound fun.