Take a dish or plate, piss on it, freeze the plate then when the plate is frozen take it an slide it under a victim's bedroom door in the late hours. The room temperature will do the rest.
1: My roommate slide a The Destructo Disk under my door last night. My room smelled so bad this morning. I think I'll get him back with the good ol' poo butter.
2: Bro slow down what's The Destructo Disk?
1: You know? When someone takes a frozen plate of piss and let's it warm up in your room?