While it may at first sound obscene, a totty pocket is actually a perfectly innocent term. It refers to a large, rectangular pocket on the front or side of a pair of pants, such as cargo pants. A totty pocket is often closed by button or zipper.
The word originated as a reference to Napoleon Dynamite from the scene where Napoleon stuffs a handful of tater tots into his pocket.
Dude, I think your keys just fell out of your totty pocket.