When I was in college and lived off campus (urban neighborhood) I left my bike in the back yard, easy visibility and access from the alley. It was about 1990, the bike was a cast-off 10sp Bianchi from a friend of my Dad's.

One day I went outside and found that my pedals had been stolen.

The bike was not locked up at all.

I will never know if that was just a prank from some college buddy that forgot to ever tell me about it