To coat the floor, walls, and sometimes ceiling of a room with urine. Can be done either intentionally or unintentionally. Noun form of gurnicking.
Man 1: Why does it smell like dried piss in here?
Man 2: Mike came in and decided to gurnick the bathroom last night.
Man 1: They really should put a light in the bathroom in this bus.
Man 2: Don't tell me you gurnicked it.
Man 1: Well, I can't tell for sure, there wasn't a light!
Man 2: You little shit!
to piss on a bathroom floor and/or wall; verb form of the word "gurnicking"
Bro 1: Dude, I'm sorry but I...
Bro 2: You gurnicked didn't you?
Bro 1: Sorry bro...