PHAT BOI Share definition Flag A dude from a Galveston Island Texas that is cool funny damn right ballin and is ready to do anything no matter what the consequences. Hey PHAT BOI what you doing tonight? PHAT BOI by PHAT_BOI_409 February 24, 2010 0 0 Get merch Get the PHAT BOI mug. Buy Now — $32.95 See more merch