When one palms another's mouth and face and then forcefully pushes their face away. Considered very offensive, similar to a slap in the face, but the muzzle usually causes no physical harm, only humiliation. Generally done to intoxicated individuals to indicate that they are no longer wanted around.
Did you see what happened with Julie and Katherine last night? Katherine was so out of control that Julie muzzled the shit out of that bitch.
the act of getting the mouth/brain/dome/head. basically getting your rod cleaned.
Bob: dude did i just see you and katie walk out the bathroom together?
Jim: yea dude, i got the muzzle.