An old Texas hobo walks into a bar and orders a drink. The bartender says, "I'll have to see your money first."
"I'm broke, sonny, but if you give me a bottle of whiskey, I'll get up on that stage and fart The Yellow Rose of Texas!"
The bartender had never seen or heard someone fart any kind of song, so he agrees.
The tramp drinks the whole bottle of whiskey, then staggers up on stage and the audience starts applauding.
Then he drops his pants and the audience starts cheering even louder.
Then, he proceeds to shit all over the stage, and everyone gets disgusted and leaves.
The bartender screams, "You said you were gonna fart The Yellow Rose of Texas! Not shit all over my stage!"
The old hobo replies, "Hey! Even Willie Nelson has to clear his throat before he sings!"