MFY! 

Mega Fucking Yawn.

To be used in say a recurring argument that can never be settled by both parties coming to a medium solution, and of which the argument does not end.

Some Redneck -"Guns are good",

Some Nonce - "Guns are bad",

Some Redneck -"Ye but Guns are good",

Some Nonce - "Ye but Guns are bad",

Me- "MFY!"

MFY! by SargeMaCDuFF November 8, 2009

MFY 

Mother Fucking Yankees

BOS defeats MFY!

MFY TO LOSE 15 GAMES IN A ROW!

MFY by CJ May 16, 2004

mfy 

Mother Fucking Yes

"CAKE IS THE BEST FOOD EVER, Y/MFY?"

mfy by thisisher May 21, 2009

mfy 

Gay acronym for Mother Fucking Yankees. Those homo's in Red Sox Nation use it because they're jealous of everything the Yankees have that they don't. Like real fans.

Gay Red Sox Fan: I love penis but it hate the MFY!
Yankee fan: Shut up faggot, go cry in the corner with your Bill Simmons column about how great the Sox are even though they just blew a 14.5 game division lead.

mfy by Every fuckin name is taken October 2, 2007

y/y/mfy 

"Yes/Yes/Mother Fucking Yes?"

Used as an alternative to "Yes/No?" when the negative is really not an option.

Are you going to the party tonight, y/y/mfy?

y/y/mfy by RunningFool January 2, 2011