The cowboy sat on a stool drinking a beer as the Mexican, also dressed in western garb sat next to him.
There was a slight nod as they looked at each other. Soon the cowboy ordered another and bought one for the Mexican also.
When their glasses became empty the cowboy bought again.
Then a third time the cowboy bought again and the Mexican grinned and spoke something but the bartender never knew what he said..
Then the cowboy seemed to be infuriated and stood up suddenly drawing his gun and shot the Mexican dead.
At the cowboys hearing the judge the judge asked the cowboy, "Why did you suddenly become enraged for no apparent reason and shoot this individual dead?"
"Well," the cowboy explained, "I tried to be friendly and he began calling me names and insulting me for no reason and finally I got mad."
"What names did he call you that made you so mad that you wanted to kill him?" asked the Judge.
"Well," answered the cowboy, "three times I bought him a drink, and each time he grinned in my face and called me Grassy Ass!"