Both a few years ago.
At work a person once wrote a note saying that they couldn't work a shift and worded it "I kinda sorta can't work". I thought I'd make fun of it because saying 'kind sorta' just seemed silly.
I threw his note away and made a new one saying "I can't work, I kinda sorta have cancer".
It wasn't enough though, I wrote an accompanying poem about having cancer adapted from "there once was a man from Nantucket" or whatever it is.
I had worked at opening the next day so I actually got to see the unfolding of my joke upon the restaurant manager. I heard her read it, I also heard her call his mother to ask if he was ok. I didn't care, I just thought it'd be a matter of her saying he's fine so I just hid as I lost it in laughter.
When I returned the other manager who was there while I made the note approached me and asked if that's what I was doing with the paper the night before, I just said yes with a big grin until she told me the details.
His mother actually had cancer, and was coming down to find out what was going on. Luckily however they managed to call her and tell her there was a mistake and everything was fine but that was one occasion I earned a reputation for having a very dark sense of humour.
With the same manager another joke of mine may have gone bad. There was a sign at work that had gone up with the cliche picture of a person laughing with her friend, talking about how awesome life is and everything is just sunshine and rainbows.
Anyway someone drew a moustache on the girl, pretty standard thing to do, but I wanted to top that. I was into the 'rapist sloth' memes at the time.
I cut out some speech bubbles and attached them with the conversation:
"ahaha, and so then he said to me, do you know what rhymes with moustache?"
"what?"
"Rape"
It may have gone bad because thinking about it I think that manager may have been raped in the past.