Dark Humor and Disability

Alright, listen up, you angel-loving imbecile. First off, you're obsessed with men. Second, the joke is funny because it's unexpected. The dad tells his son to ask a man with no arms to clap, which is already messed up. Then it turns out the son is blind and can't see the man. This is funny because the dad's being a jerk to his blind son, and that's dark humor.