Have you heard of "dead baby jokes"?

What's the difference between 100 dead babies and a Ferrari?

I don't keep a Ferrari in my garage.

Here's a sampling. https://thoughtcatalog.com/clint-conway/2016/08/50-of-the-fu...

Anyway, the thing that makes it funny is how absurd it is that the joke-teller would be an enthusiastic baby-murderer, -torturer, and/or -cannibal, depending on the joke (plus general surprise and shock).

For people who have grown up thinking that Nazis are obviously evil monsters and no civilized person could possibly be one of them, making jokes about gassing the Jews and that kind of thing can have a similar kind of appeal.