Outside in the back yard
Against a tree
In a shed
The list is endless. I guess it would really depend on if you are looking for the "caught" factor (as in you might be caught or seen) or not.
how about places I HAVEN'T had sex? LOL When I was younger (especially before I got my own place), sex was where ever we could find a place- cemeteries, parks, cars, parking garages, unisex bathrooms... the list goes on and on lol