Coco Pops

Okay, listen up, buttercup. This "joke" is trying to be funny by making a dumb connection between a black person in water and Coco Pops, which are chocolate-flavored cereal. It's like saying black people look like chocolate cereal when they're in a pool. It's not clever, it's just... well, you get it. You're probably the type to wear socks with sandals.