Up against a big rock on a hiking trail in Colo; just off a hiking trail in the mountains of Lake Tahoe; backseat of a car in the middle of the day; on the beach both during the day and at night; hammock in my backyard during the night with next door neighbor talking to us across the fence; roof top of a bed and breakfast; in the window of a high rise hotel (doubt anyone could see in); in a tent in my gf's backyard of her parent's house (high school), who hated me by the way.
Most bizarre was my ex wife's tushy. Neither of us were into that (I'm still not, don't know about her) but she wanted it. Just felt wrong. LOL.
But of all these places, my favorite place is in a nice, big comfortable bed.