What are the strangest places you’ve had sex (with another person)? And no “in my ass” answers.
As for me, I’m a member of the Mile-High Club.
I also had sex right on the curb, at the intersection of 14th Street and 9th Avenue in NYC.
I don’t really have anything to contribute to this thread, but if I had had sex in your ass it would indeed have been strange.
If you count oral, then on the DC Metro. If not, then Bullrun Battlefield, or the back of an ambulance.
Both inside Biosphere 2 and the floor of the Smithsonian Museum of Natural History were pretty strange. But then again I’ve had sex inside a dream, which is inside my head … which is a very strange place.
On a snow bank, behind a park, at night, in the dead of winter. Her butt and my knees were literally in the snow.
That was more than 20 years ago and I would never do anything like that again but, man, it was amazing and one of the top ten sexual experiences I have ever had.
I haven’t thought about this or her in years.
Under a piano in a music room at WPI.
If you help me find my car, we’ll drive out.
…which reminds me of the second strangest place I have had sex: during the New York Day Line cruise’s stop at Bear Mountain State Park, on top of a big rock, in broad daylight. A few people saw us; we didn’t care. 
In a horse barn in Germany. It isn’t that strange for any country folk on here but it was very strange for me.
The middle of the football field at university (at about 3am).
Hmm. More than one faculty office, at university.
That’s the best I’ve got.
ETA: they were grad students and not my instructors. Mostly.
I don’t think that counts.
The top of a rappelling tower at a National Guard training site, or in a curtained niche at the Pentagon, (which is not so awfully strange if you live here, but probably super strange otherwise).
I didn’t hear you objecting at the time.
Oral Sex: Movie theater.
Actual sex: Either a church parking lot or the side of the highway out in the desert. Both late at night.
Back of a greyhound bus.
I guess I should have clarified. Too late now.
The horse thought it normal?
On a bench behind the American Airline Flight Attendant Center trying to make curfew.
Uncle Frank’s bed.
There’s a clause or two missing from that second sentence. Unless “Curfew” is a baby-name, I’m not getting the connection. 
