Let's see...
-Various cars
-Showers (gym, dorm, personal)
-On a rooftop
-Tons of trees/shrubbery
-Almost every state I've been to
-Hotel rooms
-Plane while flying to Vancouver
-Lake Erie/Huron/Michigan
-Tents/sleepingbags
With the exception of planes, cars, and states (except New York state, I haven't travelled much in the US), I'm with you on those. Whenever I go camping there's usually somewhere in the sunshine where I jack off.
That said, I never like leaving messes in hotels, B&Bs, friends' houses, or anywhere else someone's going to have to clean it up. I just feel like a jerk doing that.
To add to the list:
- various bodies of water worldwide
- the snow
- snow caves
- underground
- various hammocks worldwide
- a few faces
I've always wanted to jizz in one of those hotel Bibles and then slam the thing shut (I don't like having other people's lifestyles pushed on me), but I've never worked up the nerve to do it.