There have been plenty of movies and shows based on this so I guess I'm more confirming a poorly kept secret than I am revealing it, but;
If you go out to eat in a college town (esp if it's a state school,) there's a good chance that almost every employee (managers, bartenders, servers, you name it) is drinking or smoking pot out back, if not in the middle of an active bender. We'd fill our water bottles with alcohol, make food for our stoner friends in exchange for drugs, take shots in the walk-in fridge, roll on Molly while cooking, run out back to puke, and rally for the rest of our shift. After closing we'd meet up with other industry friends, usually at a bar where one of them was still working, close that place down, then pair off and hook up in questionable places.
I've had sex on restaurant rooftops and patios, in supply closets, behind the stacked pallets in dry storage, and in the manager's office. I witnessed others get it on in booths, on top of the video poker machines, and even on the bar itself. Thankfully never where food was prepared, but that was pretty much the only thing that was off limits, and only within my social circle. I can't speak about others.
I'm a boring elder millennial now, but every once in a while I reminisce about working in the service industry. I don't think I appreciated how much freedom I had, I was too busy worrying about money, school, and relationships. I definitely wouldn't do it again, but I'm glad I got to sow my oats, or whatever.