I've worked in catering all my life. I have a few stories (which I shall tone down a little)...
...customers place their used crockery on an automated carousel and I clear this away, giving things a wash. One day a tray came around and as I swept the rubbish in the bin my (THANKFULLY gloved) hand came into contact with something cotton and wet. I looked and realised I had just touched a used tampon.
...another time a customer pulled down her knickers and had a little poo. Then another customer complained and ranted at my colleague who rightfully refused to touch said log roll.
...sometimes customers don't like what we provide (and I dont blame them, its a faceless multinational with overpriced food and drink with very few staff left to serve it), so they balance a full paper cup of boiling coffee on an empty one and place the whole thing on a tray to the top shelf of the carousel. A few of us have nearly been burned, it was just instinct in feeling the balance and the weight of the object that makes you leap back.
...one of the students that came in last year (we get loads, they get a discount, and we get to know the faces) walked up to a bin with her rubbish and simply threw it on the floor in front. Not even an attempt to push it through the swing door.
...one of the toilets in the Gents changing room didn't get flushed after someone bombed a curry down there.
...few weeks back a fella came in, sat down for a meal with his family. I was emptying the bins at the time, just walked away from one I'd just changed the bag on and heard an almighty crash. He'd only thrown his crockery into it.
...customer came up to me one evening and said "someone has left his dentures in the gents by the sink!" I walked in there expecting to find a pair of gnashers, what I actually found was a box of around 12 or more display pieces a technician might tour with to show their handy work.
I could go on.