this is when you sit in a stall in the mens room until some guy goes in next to you. You then wait until the man has completely lowered his trousers and is in the process of blastin his dukey. You then proceed to stand on the toilet (if possible), lower your pants, and let out a pisser over the stall wall and onto the man next to you. Then zip up and run like a motherfucker!!!!!!!!!
This can also be done with two people on either side of the man, both in on the joke. Sometimes called a chi-town super sprinkler
Me and Daniel gave our teacher a chi-town sprinkler while he was on the john. He never found out!!!!!!