It would be so great if he just washed people's cars and then was all like, "Oh man, somebody just washed your car but it totally wasn't me." Then he films their reactions as he tells them, "Gotcha. It was totally me. I do hilarious pranks on YouTube." And that's it. That's the joke. The joke is that the jokes aren't funny and they're not supposed to be which is like a meta joke in itself. But nobody understands because that's really hard to explain to people. So he just exists in your own bubble of inside jokes of which he's the only one that's privy. I realize now that I'm describing myself as I type this out.
