gag-a-fart Share definition Flag A condition where a person starts gagging and farts in unison with each gag. She started gagging and farting at the same time during oral sex. A gag-a-fart is a real mood crusher. gag-a-fart by Gag-a-ster August 22, 2011 0 0 Get merch Get the gag-a-fart mug. Buy Now — $32.95 See more merch