Erogenous zones in places you wouldn't expect

Do you have any erogenous zones in unexpected places? How did you discover or trigger it?

I found one on myself that I've never heard of. Lately I've been trying to develop my nipple sensitivity. That has been going pretty well. For me it only really works through a shirt, using the 'slow flick' technique I read about in a thread here somewhere. I feel most of the transferred sensation in my balls, but it's still very nice. Anyways, today I took a shower, washed my hair, and, for some reason I decided to turn around to rince out the soap, as if I had long hair. When I tilted my head back and the water started hitting my forehead, it was like...walking into machine gun fire of pleasure. Every drop of water felt like a flick of the nipple. It was so intense and unexpected that I almost stepped out of the water on reflex, but I managed to stay and enjoy it. The feeling didn't transfer anywhere else besides my head, but it did almost feel as if it went deep into my brain. It was so intense that I could only stand it for about 30 seconds, but I had aftershocks for about 15 minutes. I'll try it every shower from now on and see what I can do with it. I can definitely see a forehead based super-O happening if I can connect it to my genital area somehow.
Has anybody else had that happen? Is there a name for it?