A fork of Rural Dictionary
Post-Coitus Flatulence. Farting that can occur after sex. May be mistaken for beer farts if sex occurs after a night of heavy drinking. Should beer farts be mistaken as PCF, you may end up literally shitting the bed.
Girl: I'm exhausted. Let's cuddle. Guy: Sure Guy: Oh no. I'm going to ruin the moment. *FART* Girl: PCF is so gross.
The extra beer you bring to a party to ensure you will have enough to get yourself drunk. Commonly misspelled as "insurance beer."
Guy 1: Well I've got this 12-pack for myself, but I don't know if it'll be enough Guy 2: Grab some ensurance beer, better safe than sorry.