Wondering Wanker
A Wondering Wanker is a person who engages in the simple act of flogging the dolphin in a public restroom, department store changing room, or other random public place. Normally the Wondering Wanker is always horny and gives no regard to where he sprays his baby gravy.
Bro 1: Dude, I was dropping a grumpy at the crapper in Best Buy the other day and I think the guy in the next stall was whacking it!

Bro 2: Oh gross, you were sitting next to a Wondering Wanker...