1) When a man urinates with an erection inside of a woman's vagina.
2) When a man urinates inside of a woman with a condom on, pulls out, ties off the condom and slaps the shit out of his bitch with the piss-filled condom.
3) A wizard bar in Harry Potter. No piss involved.
Doug: Yo, why is your biznitch so pissed off at you?
Jordan: That's ironic. She's pissed because I gave her a leaky cauldron and my piss got all over her.
Doug: Isn't that in Harry Potter?
Jordan: You're such a fucking virgin. (explains alternate meaning of leaky cauldron)
Doug: *High Five*