Best prank ever:
Invite him and a couple other people to the movies. Pick out a row of where you wanna sit b4 hand. So when you guys walk in..you can be like oh lets sit there. Tell every1 to meet you there. You on the otherhand get to the movie theater 20mins b4 every1 else arrives. Go over to the seat you want him to sit in and stick a needle/pin sticking upwards. So when he sits..it'll poke him in the ass. Right under the needle/pin on a piece of tape or just on the seat, write: "Welcome to the wonderful world of AIDs, bitch."
Of course the other people thats coming to the movies will have be in on this..so you guys can work together and seat him at the right seat without him knowing.
So anyways after he sits and jumps up reading that..he'll go crazy and run home or the doctors. Over the next week he'll be getting tests done..showing if he has aids or not. He'll be in a total fucked up state of mind. While he does that, send him a card saying: "This is payback for the wasabi bitch. Got yah!"
Then have a good laff over it at a local pub. And let us know how it went ruk. Its a lil work..but if u wanna git him good..this is a really good way.