Definitions by ak215

M.F.B. 

Monogamous Fuck Buddy
Refers to exclusive fuck buddies who aren't in a "relationship" but only fuck each other.

Are not obligated to do couple's activities, except sex.

"Hey, can we just be M.F.B.'s?"
"I'm her M.F.B."

M.F.B. by ak215 November 13, 2018