I don't know which one is the strangest, but I used to do long bike trips, and here are some candidates:

• In a tunnel under construction in the middle of a Swiss mountain. I put a yoga mat on the road and slept on it. The tunnel was lit, but it was closed to traffic. There was a lot of water dripping from the ceiling.
• In a toilet cubicle in the bathroom of a hostel that wouldn't let me stay
• In bus shelters
• in the middle of a roundabout somewhere in northern Italy. It was midnight and I was tired and didn't have the time to look for anything better.