MF Swear Share definition Flag To Middle Finger Swear on something. Like a pinky swear except strongger. "I'm going to buy you an iPod if you pay for half" "fine, but MF swear on it first." MF Swear by Mastersam0 June 11, 2008 0 0 Get merch Get the MF Swear mug. Buy Now — $32.95 See more merch
