In case it's not clear, when a sociopath explains away bad behavior by saying it was "just a joke", they don't mean they were making a joke to be funny. These so-called jokes are a test to see who is in-group and who isn't. If you think it's a good joke, you're part of their group. If you don't think it's a good joke, you're their enemy.

This is why their humor sucks. They're not making jokes to be funny, but to weed out the people who don't think they're funny.