Muck Fuffin Posted in M Best definition Muck Fuffin Friendly way of saying Fuck Muffin. Formed by switching the m and the f. Used often as a substitute for the yelling “shit!” John: Hey you’re gf’s breaking up with you. Jack: Muck Fuffin! How satisfied are you with the definition? Looking for Muck Fuffin meaning? Delighted that you discovered the greatest determine on our web site! Recently this definition was actually observed 99 times.