marshbag Share definition Flag A lie that is over the top and is in no way believable in any way, shape or form. "Yo brehs, i boned three college broads this weekend!!" (I'm 5"4) "ye okay marshbag.." marshbag by MARSHBAAAAHHHGG March 2, 2009 0 0 Get merch Get the marshbag mug. Buy Now — $32.95 See more merch