KTMF Share definition Flag KTMF stands for Kill the mother fucker. You use it when someone you strongly dislike has made you very mad and you tell someone one. ex. My teacher makes me so angry i could just "KTMF!" KTMF by Bochee-Bee March 22, 2011 0 0 Get merch Get the KTMF mug. Buy Now — $32.95 See more merch