Some big-mouth wanna-be road player rolls in after a big tourney and asks who won. Only 15 people left in the room. He tells the winner chilling in a chair I’m 570, you’re 693?, I’ll play you 10 ball race to 7 even you just have to make the money balls left handed. ....
There is a very old Mark Twain story that's about the same. Evidently pool players are slow to learn.
But in terms of dumb, I don't think your story holds a candle to a group who took the pool balls to the carom table, racked up eight ball, and took several shots before they figured the table was funny. It turns out the balls won't actually fit into the dust holes at the corners. They tried pushing one in by hand.
The Twain story:
Speech, April 24, 1906
The full text:
The game of billiards has destroyed my naturally sweet disposition. Once, when I was an underpaid reporter in Virginia City, whenever I wished to play billiards I went out to look for an easy mark. One day a stranger came to town and opened a billiard parlor. I looked him over casually. When he proposed a game, I answered, “All right.”
“Just knock the balls around a little so that I can get your gait,” he said; and when I had done so, he remarked: “I will be perfectly fair with you. I'll play you left-handed.” I felt hurt, for he was cross-eyed, freckled, and had red hair, and I determined to teach him a lesson. He won first shot, ran out, took my half-dollar, and all I got was the opportunity to chalk my cue.
“If you can play like that with your left hand,” I said, “I’d like to see you play with your right.”
“I can’t,” he said. “I’m left-handed.”