outersnatch
When a girl is so incredifat, that her rolls make her vagina completely inaccessible. When you're sexing her, you're just having sex with the outer flab folds that hang off her thighs and her fupa. These flab folds give a similar sensation to sexing an actual snatch, but they are on the outside of her body.
I beer goggle humped this fat chick. It wasn't bad, she had a supple outersnatch.