Two (2) guys fucking one (1) girl at the same time. The man getting the blow job must be all business up front, while the guy fucking the girl must be having a party in the back, hence the Mullet. Business up front, party in the back
Muller: Did you hear, Bill and Justin took Sarah home last night?
LTC: No what happen?
Muller: They gave her the Mullet.
Muller: You know Bill all business with the talky hole while Justin was have a party in the back.