If It Ain't Broke

Alright, listen up, buttercup. The joke is that Daveon is too stubborn or satisfied with the way things are to try anything new. He uses the saying "if it ain't broke, don't fix it", meaning if something is working fine, there's no need to change it. It's funny because most people should be open to new things, but not Daveon, apparently. That's why the author thinks he is dumb.