LOL, That's a good one. I take this kind of stuff in stride and some times it turns out to be a fun game. Besides, if I wanted a serious game I wouldn't be looking in a bar for one anyhow.
My favorite was a time, in a bar, I was playing this guy for drinks. He keeps making up these rules as we go and I keep asking him is there anything else? Every time the answer is no until I make the next shot and then there is a new rule. Finally I get down to the 8 ball, I call it in the corner and shoot. The eight rattles the pocket a bit but drops right where I called it.
Sure enough this moron jumps up and yells " Yeesss, I'll have a Bud Light"
I ask what he is talking about and he say I didn't call a bank shot! I explain to him that it was not a bank shot but his mind cannot be changed.
As far as he was concerned if it touches a rail it IS a bank!
So I get him his beer and with a smile I ask him if he would like to play again, now that I got the rules down.