[Police Joke]Manners, Poo, and Shut up

So there are three men in a truck driving in a desert. Their names are Manners, Poo, and Shut up. Poo falls out of the truck but Manners and Shut up don't notice so they keep driving. They finally stop at a gas station and Manners goes back to look for Poo while Shut up stays at the station.

A policeman goes up to Shut up and asks "What's your name?" and Shut up replies "Shut up."

The policeman says" WHAT'S YOUR NAME?" and Shut up replies "SHUT UP!" and finally the policeman goes "Where are your manners?"
 
Shut up replies "Picking up Poo."