I had this elementary student for two years who had a dark sense of humor like me; we got on like beer and chicken (in case you aren’t aware, beer and chicken are partners).
One day, we were reading a story in his class about a young boy and his grandmother called “The Raft” (not to be confused with the excellent short story by Stephen King that made it into the first Creepshow movie); there was a picture in the textbook of the two sitting on a homemade raft. The young boy was wearing a life jacket; the grandmother was not. When the students asked why she wasn’t wearing a life jacket, the words tumbled out of my mouth before I took the time to think about them: “Maybe they just figure that since she’s so old, it doesn’t matter if she drowns.”
If the other students got it, I hope they knew I was joking!