Back in the 90's I worked at a large outdoor retail sports company for part time work (mostly nights or weekends), but more importantly, picked up some great employee discounts on merchandise.
One girl I worked with never seemed happy, just kind of like a fuddy duddy who didn't like her job. One night she seemed all happy and excited, and I joked with her that she must have had or is going to have a hot date.
She reported me for sexual harrasment, the manager had to write me up. Pretty much one of the few times I've ever been reprimanded in my life working, and it was on a part time job I didn't need.
Looking back, yes, I was wrong about the comment I made and I did learn my lesson. I worked with her for over a year before that and never a problem until I made that comment only in jest and I honestly didn't mean anything by it.
It was a learning lesson on my end.