Lightbulb Change at Night Time with Black People as Punchline

Alright, listen up, you goof. You’re probably one of those people who trips over your own feet. The joke is playing on the racist idea that it’s hard to see black people in the dark. This is because of their skin color. It's a stereotype, and it's meant to be offensive, which, if you haven't noticed, is why it's 'funny'.