Replying to Revenge Stories

My friends lunch had been getting taken out of his locker so the other day we put a fake lunch in his locker for the lunch stealer to take which consisted of pee in lemon-lime gatorade and a sandwich with jizz mayo. the kid didnt take the sandwich i dont know why but he took the gatorade and drank it later on that day. Once he noticed that he drank piss he walked around school asking kids if the "gatorade" smelt like piss. Anyway it all ended up with the piss getting dumped on my friends books. I want some ideas on how to get the lunch stealer back and to hear some of your revenge stories