They have to provide the the correct follow-up to the phrase "I bet I can tell you where you got 'dem shoes."
Someone once told me that they were down in New Orleans on a buisness trip with a female associate... they were walking around the Quarter and one of those hustlers came up and tried to bet him $10 using the "I bet I can tell you where you got 'dem shoes" line.
He knew the con, so he replied "Well, my shoes would be too easy to guess. But I'll bet you can't for my wife."
The con artist gave the standard response, "She got her shoes on Bourbon Street in New Orleans," to which the man replied, "No, my wife's shoes are on her feet at our home!"
He didn't pay up....