MNBF 

MNBF = My New Best Friend

Hey MNBF!!! How you doing?

MNBF by Jonesy no fool June 11, 2006

mnbf 

Pronounced minnibuff
Mole Nose Brace Face
referring to a girl who has a mole on or around her nose and of whom also has braces.

"Dude, I nailed a MNBF last night."

mnbf by Thealaskan April 22, 2008