At any camp or sleepover involving junior high boys, the time after "lights out" to begin making farting noises, real or imitated.
The youth director is asleep - it's fart thirty!

(sleepy camper) What time is it?
(friend rips one)
(sleepy camper) Oh. It must be fart thirty! (responding in kind)
by bob beeflips November 16, 2011
Get the Fart Thirty mug.