GTFUTM Share definition Flag Short for "Get The Fuck Under The Misteltoe". First used by the fans of the popartist Justin Bieber, also known as beliebers. Girl: I don't want to kiss you right know... Boy: GTFUTM GTFUTM by A belieber who beliebes November 16, 2011 0 0 Get merch Get the GTFUTM mug. Buy Now — $32.95 See more merch