DFMT Share definition Flag A shortened version of the phrase "Don't Fuck My Tities," which is commonly said when you don't want someone to bother you because you have recently been upset by something serious. 1: "Dude, I got an F on my math test, DFMT's right now." DFMT by Yaabuddy November 9, 2009 0 0 Get merch Get the DFMT mug. Buy Now — $32.95 See more merch