A prank wherein you hang out in front of an apartment complex, waiting for the inevitable pizza delivery guy to show up (with someone else's order) - and you buy it. A real-life "man in the middle" attack, so to speak.
Roommate: "I'm bored - anyone down for Pizza Roulette?"
You: "Hell yeah - lemme grab my smokes!"
(out front of the building, a few cigarettes later, a pizza delivery guy shows up)
You: "Hey, is that pizza for apartment, uhhh.."
Pizza Delivery Guy: (looks at box) "Apartment 231?"
You: "Yeah, that's us!"
(you pay, he leaves)
You: "Ahh, shit. Anchovies and extra olives - nasty!"
Guy In Apt. 231: "Hey, where's my motherfuckin' pizza?"
Pizza Shop: "Uhhh.. it was delivered and paid for..?"