Bob Bartops's line about the "little old lady that hasn't bluffed since the Truman Administration" reminded me of a story I once read about Johnny Moss.
Sometime in the 1950's a $400-$800 California Lowball game broke out at the Desert Inn. It was an ongoing game and there was so much money in play that some of the guys were bringing their money in in cardboard boxes.
Johhny Moss wanted to tag the game but the problem was he had never played California Lowball--and he wasn't gonna dump a bunch of money to learn how to play. He knew about the little old ladies of Gardena. They had a reputation as tough ass $20 lowball players. So tough that the guys didn't like playing with them, so they mainly played among themselves.
Moss went to Gardena and sat in with the little old ladies for a week. They must have taught him pretty good because he went back to the Desert Inn and wound up busting the $400-$800 game.