yflmd Share definition Flag an acronym for "you fuck like my dad" which originated from a song entitled so by the band Giant Drag, on their album Hearts and Unicorns. "I can't see you anymore, David." "Why not? I thought we were in love." "Why not? 'YFLMD' is why not." "Huh?" *click* yflmd by cheree nk November 8, 2007 Get the yflmd mug.