Drug Dealer vs Prostitute

Listen up, buttercup. This joke is funny 'cause it's nasty! It's saying a prostitute is like a drug dealer because they can clean up their, uh, "product" (crack, get it?) and sell it again. Basically, it's a low-brow jab at both professions. But hey, you probably still don't get it 'cause you're still trying to figure out how to tie your shoes, genius.