FMBB 

an extremely fat man (or boy) who's shoulder blades look like tits or boobs thus FMBB (fat man back boobs)

dude 1: woah that kid is fat

dude2: FMBB!!!!

dude1:hahah hell yeah

FMBB by biggieblack March 18, 2010

FMBBFL 

(Pronounced Fumb-Buffle)

Acronym for the phrase: Fuck my brother's best friends' life. also, used in place of FML because it sounds funnier.

Kari: "My little brother is yelling at kids on xbox live through his mic."

Gabe: "ORLY?"

Kari: "Yes, and his best friend just got called a queermunch kamakazi douchemuffin by a ten year old. FMBBFL."

Gabe: "Yes, FYBBFL"

*ticklish laughter*

FMBBFL by Toodles Punch April 19, 2010