…over the years whenever encountering one of those perfectly circular 3-inch holes drilled so precisely through metal toilet partitions is "How? When? By whom?"
It would obviously require a metal cutting hole bit and an electric drill, but that raises the obvious question of when such a task could occur. It would not be a quiet process by any means. And by whom? Obviously someone who had after-hours access to whatever facility it was when the place was locked up— and the chance of being confronted was next to zero.
I've seen quarter-inch thick steel plates ripped off and thinner metal bent back from the holes they were covering, so I guess there's just no limit to human ingenuity when something stands between two horny men.
In college, I was awed by the ones in 1/2" MARBLE.