[Aside: Well, a police officer is still a cop in NYC and while I haven't heard G-man in many a blue moon, I still hear one-dollar bills referred to as bucks, five-dollar notes referred to as a fins and a ten-dollar bill referred to as a sawbuck. If a Benjamin is a reference to the hundred-dollar bill, the Tubman for the twenty cannot be too far behind if some people have their way (though I hope they choose to use a more flattering photo of her than the one I have seen).
I can still remember when our older brethren referred to the large size currency once in circulation as horse blankets. Occasionally, you may hear ducats used as a reference to money. And while a disme sounds dismal, I have never heard anyone in the hobby object to the ten- and twenty-dollar gold pieces being referred to as "eagles" and "double eagles," respectively.]