1) noun - A derogatory term given to a hot bitch in the car adjacent to your's at a stop light; often shouted out in an exuberant show of excitement.
2) verb - The act of "müshing" up a bitch's pussy during sex.
sup' girl. You gonna let me get all up in that little fucking ham sandwich. I'll müsh mash that shit up. Let me see that boot buckle meat girl.