a bag that you put extremely ugly women in right before sex; upgraded version of the paper bag trick (see paper bag); user must create holes in the bag for only the essential body parts to be accessible i.e. vagina, ass, boobs, mouth, nose(for breathing, except in S&M where no hole for breathing is allowed)
Friend: Dude, I do not know how in the world you can fuck your girlfriend...that girl is hideous.
Boyfriend of the ugly ass girlfriend: Relax man. A body bag with only holes that let me see and touch whats important does the trick. Add in a dark room and you can imagine you are fucking any girl you want.