As a student in 3 universities decades ago, I only came across spy holes.

At the last university at which I taught, however, there was a sauna suite with sauna, steam room and whirlpool. Some days were men only and it was far from unusual for guys to be feeling each other and masturbating each other in the whirlpool or having sex in the sauna, steam room or locker rooms.

The university tried monitoring these sessions to prevent sex but some of the suite staff joined in so they ended "men only" sessions.