He says to the waiter, "I want coffee." The waiter says, "Sure, coming right up."
He gets the teen a tall mug of coffee, and the teen drinks it down in one gulp, picks up the bucket of shit, throws it into the air, blasts it with the shotgun, then just walks out.
The next morning the teen returns. He has his shotgun in one hand and a bucket of dog shit in the other. He walks up to the counter and says to the waiter, "I want coffee."
The waiter says, "Whoa, punk! We're still cleaning up your mess from yesterday. What the heck was all that about, anyway?"
The teen smiles and proudly says, "I'm training for upper management position: Come in, drink coffee, shoot the shit, leave a mess for others to clean up, and disappear for rest of day."