I have been doing a lot of what this cowboy does lately, so see if you can guess before you hit the punch line!
What I had to do in Texas...
This is a pretty old one, but I figure it's worth telling just in case people \haven't heard it.
In a typical wild west desert town, a typical rugged cowboy/drifter type rides his horse up to a saloon, then ties it to the post and saunters in for a drink.
While he's drinking, some other patrons think it'd be funny to pull a prank on him, so they go untie his horse and lead it away.
The visitor pays his tab and walks out, yells "What in tarnation?!" and stomps back in, a glare on his face and a hand on his holster.
The visitor yells so the whole saloon can hear, the pianist abruptly stopping. "Alright you varmints! Listen up and listen good; someone went and stole my horse, so here's how it'll be: I'm gettin' one more drink here, and by the time I finish, that horse had better be back at his post, or else I'm goin' to do something awful I did back in Texas. I'm warnin' ya all right now; don't make me do what I had to do back in Texas!"
Everyone at the bar is terrified, so when the visitor has finished his drink, and walked out again, sure enough the horse has been returned. The visitor says "Much obliged", swings up and is about to ride away, when one patron who followed him out says,
"I'm curious, pardner, what was that awful thing you had to do back in Texas that you didn't want to do here?"
The visitor replies, "I had to walk!"