I’m about 95% sure this was an animated Flintstones episode. But I could be wrong, because I can’t find a clip or reference to it anywhere! Maybe is was the Jetsons, or one of the live action Flintstones movies. (Not a completely original bit, but I’m pretty sure it’s at least somewhat connected to the Flintstones cartoon.)
Fred and/or Barney are doing some transaction with a thin man–maybe at a carnival. I think the man asked them for change for a large bill.
The conman counts the money, then decides he wants the large bill after all. Maybe there is some other money-shuffling and fast-talk in between.
In the end, the conman walks away, and the “good guy(s)” realize they have no money and have been swindled.
Thanks for any help!