Don't mess with old people.

He walked up to the first saloon he came to and tied his old mule to the hitch rail. As he stood there brushing some of the dust from his face and clothes, a young gunslinger walked out of the saloon with a gun in one hand and a bottle of whiskey in the other.

The young gunslinger looked at the old man and laughed, saying, "Hey old man, have you ever danced?"

The old man looked up at the gunslinger and said, "No, I never did dance. I just never wanted to."

A crowd had gathered by then and the gunslinger said, "Well, you old fool, you're gonna' dance now," and started shooting at the old man's feet.

The old prospector was hopping around and everybody was laughing. When the gunslinger fired his last bullet, he holstered his gun and turned around to go back into the saloon. The old man reached up on the mule, drew his shotgun, and pulled both hammers back making a double clicking sound.

The gunslinger heard the sound and everything got quiet. The crowd watched as the young gunslinger slowly turned around looking down both barrels of the shotgun.

The old man asked, "Did you ever kiss a mule's ass?"
The gunslinger swallowed hard and said, "No. But I've always wanted to."

The lessons from this story are:
1. Don't waste ammunition.
2. Don't mess with old people.