Yo Mama at Red Lobster

Listen up, you donut. This "yo mama" gag is all about makin' fun of someone's mom. In this case, the joke is that yo mama is so nasty that she had to bring her own crabs to Red Lobster. She's likely bringing a disease, you get it? It's funny because it's implying yo mama is so nasty that she ain't gettin' any crab at Red Lobster.