Kahin

Hey, listen up, buttercup. The "joke" is a play on words. "Kahin" sounds like "Cain," as in, you are asking, "What do you call a Cain?" But really the person is saying "What do you call a retard? Cain." It's like, so dumb, it's almost impressive how not funny it is. You probably laughed though, didn't you?