Fuck your mouth, otherwise said as "fuck yo mouf" is the reply to a "slam" or a "burn." Generally stated after a person says something offensive, wrong, or a lie.
Man 1: "Yo, my hommie just rolled up on some bitches and hit it hard last night."
Man 2: "Man, that was my sister. Fuck yo mouf!"
Man 2: "Man, that was my sister. Fuck yo mouf!"
by CGPierce May 1, 2008
What happens when someone is served an open palmed disrespect, often utilizing a tool. Is seen as a deserved act of revenge after a period of humilation.
In that movie Wanted, the main character slapped the fuck out yo mouf when he bashed his cheating best friend with that keyboard. It said, "Fuck You"
by Supa Nigga October 5, 2009