The resulting effect of walking after recently shaving your public region. The feeling and sounds is akin to sandpaper being rubbed against your genitals.
Joe: How's it going?
Andy: Bad. My crotch has got a real bad sandpaper effect going. I shaved my pubes last night.
the act of making sweet, consentual love to a woman's scratchy armpit and ejaculating therein
Man: "Did u see that chick dude? I would sandpaper sailor her like there's no tomorrow, I don't care how pregnant she is."
Dude: "Here's to all those poor, unfortunate seamen."