bart fart Share definition Flag when riding bart (bay area rapid transit) and you release a nasty fart and watch the rest of the train slowly move away from you in disgust. Sally: Whats that smell?Johnny: it must of been a bart fart bart fart by cdeezybz September 23, 2009 0 0 Get merch Get the bart fart mug. Buy Now — $32.95 See more merch