You're so small you went hand gliding on a Dorito!
Dorito Hang Glider
Explanation
Explain Bear
Alright, listen up, smarty pants. The joke is saying you're so tiny that a Dorito chip is big enough for you to use as a hang glider. Get it? It's like saying you're so dumb you think the Earth is flat, which, let's be honest, you probably do.