MEF 

Mother Everyone's Fucked. Derived from the example of MILF as noted in the classic movie, "American Pie". This term is used for a female who use to be a slut, but then settles down, gets married and has a kid.

"Damn, I ran into Jen today and found out that she's married and had a baby. You remember Jen don't you?? What a MEF!"

MEF by KiKKi January 14, 2006

MEF 

Mortal Enemy Forever. The opposite of BFF

He was once my BFF, but then he committed a grevious crime and became my MEF

MEF by DoomLord June 25, 2009

Mef 

The Queen of the Geeks. Speaks with a heavy lisp through a retainer and makes many 'alien' hand gestures to get points across. Watch out for flying saliva.

Mef: I AM THE COMMANDER OF THE UNIVERTHE!
Followers: *kneel down and praise* WE ARE NOT WORTHY!

Mef by Steezus January 3, 2004

mef 

to do something half assed
coined by mathias aka teethi13. IM him.

you just pulled a mef

mef by cambray January 3, 2004

mef 

an insult to someone who takes bout themselves or something that belongs to them

Suzy:omg i got these awesome jeans at the mall i look so sexy wit them!!
Marty: ur such a mef!

mef by TINA March 2, 2005

mef 

Male Ejaculation Fluid.

eew, you got mef on your sheets.

mef by Cxiara April 30, 2005

MEF 

Mom Everyone Fucks

Your mom is a MEF, she let the whole crew run a train on her

MEF by Nworb Nosaj July 13, 2016