Denim Defect

Why do all my jeans wear out crotch-first? I ask because I was hopping into a fairly new pair this morning when I noticed the denim looking a bit thin below the zipper.

"It's probably just your thighs rubbing together when you walk," a co-worker suggested when I brought it up at the office.

"Or maybe I just really like to dry hump," I spat back.

But yeah. It's probably the thigh thing.