A year ago my boss at the time wanted to clean up the office and asked the sales team to do it(cleaning isn't my usual job but whatever, get paid the same either way). While carrying around a bunch of old filing boxes, found a dusty $100 bill that had been accidentally left in it.
Thought about pocketing it since I was underpaid, but then thought that it might be some sort if an honesty test that he had planted there, and went to give it to him.
From the way he reacted I could tell that it wasn't a plant, and he didn't particularly care that a spare $100 had been randomly found- an amount of money that would have made my day meant nothing at all to him.
I felt like a complete idiot for giving it to him and went back to work cleaning for him the rest of the day while he left the office early and drove off in him bentley.
Learned from my mistake and have never since worked a minute of unpaid overtime etc.