"SCOOT WANT TAXI!" Ok, maybe I do but can't make it there because yo mama is so fat he can't hear me on the other side.
Yo Mama Too Fat
Explanation
Explain Bear
Listen up, buttercup. The joke is all about a 'yo mama' gag. The joke teller wants a taxi, but your mom is so obese that she blocks sound. It's funny because it uses hyperbole to exaggerate her size. And because you're laughing, I'm guessing you're not on a diet anytime soon.