An FCC-friendly way of saying "unable to be fucked with". Coined on the Cartoon Network Adult Swim message boards, later displayed on a bumper between episodes of Family Guy and Futurama to millions of American viewers.
Man, don't mess with that kid. He's unfukwitable.
Acronym for stupid mother fucker
, often used in conjunction with l33tsp34|<
, or more commonly, simply as a friendly expression used during internet chat or to spam
My roomate just walked in and puked on his bed. What a smf.
You locked yourself out of your car! SMF!!!111one111