Is getting a girl expelled from school after sending topless pictures of her to an administrator considered a prank? If so, that.
If not then I'd like to submit the following: I randomly messaged this one kid I went to school with on AIM. I only meant to screw around with him for a while - maybe give him a fake number if he asked me for one, BUT he ended up asking "me" out on a date the coming Saturday. I couldn't turn it down, so I said yes and to look nice, meet me at such & such location, all that good stuff. I (the REAL me) was actually invited to come along to this outing by the kid's sister along with another friend of mine who was in on everything, so we got a first hand look on how everything went down. Obviously, there was no girl. The kid was broken hearted, real somber throughout the movie. I think he even shed a tear or 2 on our way out. Oh, and he bought the "girl" and a friend she was going to bring a ticket to the movie. He never got his money back. It was great fun.
He never found out, by the way.