Fart-on Share definition Flag When someone sits on guy’s lap and farts so strongly that the vibration results in the guy getting a hard-on Dude, Jennifer sat on my lap and she let one loose and I sprung a fart-on! Fart-on by KDS117 December 31, 2017 0 0 Get merch Get the Fart-on mug. Buy Now — $32.95 See more merch