My most unusual place was at my ex bfs work place. He worked at a feed store..and I took him some lunch to work. He was the only one there and his boss went to lunch...and we did it on a pile of corn. Wasnt too comfortable but it was nice.
Anyway, the unsual place I had sex for me is in the toilets (ladies) in the shopping mall. My ex gf got horny when buying some lingerie and wanted it 'now' kinda thing so no options but the rest room, lol!
Fields, woods, swimming pool changing cubicle, swimming pool, back of a car, sauna, changing room, sea, beach, cinema disabled toilet, motorway lay-by etc. etc.