I have ironic sense of humor, along with some dark and random mixed in there. I noticed a lot of NF's are like that. After I became friends with my ENFJ friend around my middle school years, my humor started tuning into her's, but then again before that I was really reserved, so I don't even remember what I thought was funny. Her and I were like, humor twins. We always thought the same things were funny.
I will say CERTAIN toilet jokes can be funny. Very select ones. As far as cruelty goes, not sure if dark humor is exactly in that category, but I'm sure some of it is, but there is a point where something just becomes way too bad that it isn't dark humor anymore, it's just disgusting. I'm not as much into physical/appearance jokes either. I read somewhere that it was usually more of an S thing.
But if anything, random always works for me.