Rapper's Payment Method

Hey, listen up, buttercup. This joke is about how rappers, those dudes who spit rhymes, might pay for their stuff at the store. The punchline is a play on words: instead of just using "cash", it's a "sick flow of cash." See, "flow" is also a term for how rappers deliver their rhymes, which makes it kinda funny. Don't hurt yourself thinking too hard.