Q: What do a prostitute and a vacuum have in common?
A: If they stop sucking, you can smack them until they start again.
Listen up, dummy! This "joke" is saying prostitutes and vacuums are similar 'cause if they ain't doin' their job (sucking), you gotta smack 'em to get 'em goin' again. Get it? It's funny 'cause it's basically about treating people like objects. Which you probably do all the time, you Neanderthal.