A cowboy stops his horse

A cowboy stops his horse next to a saloon.

He dismounts, enters the saloon and tell the barman:

Twenty bottles of whiskey! My horse is thirsty.

The barman gives him the order, the cowboy pays, the horse drinks it all.

Hey! – tells him the barman. – Ain’t you going to order some for yourself?

Are you nuts? I’m driving!