The same as Masking but it involves placing the entire man package, thats balls and all, in someones ass during intercourse. This way its a sport two men can enjoy as well as heterosexual couples.
Keith: Are you alright Trev? You're walking like you've had an accident.
Trev: Na man last night me and my lady tried a bit of Rear Masking and that shit aint no picnic on your ballsack.