A Two Bit Diner is a restaurant with a special priced to the two bit coin.
A bit is one eighth of a silver coin. A two bit coin is a quarter of a silver quarter. The old US silver quarter contains 0.18084 troy ounces of silver. The price of silver varies. When the spot price of silver is $38.70 per troy ounce, the "melt value" of silver quarter is $7.00.
The price of silver is dynamic. To be true to the gimmick, a two bit diner would periodically look up the price of a silver quarter and change the special.
Many restaurants have taken to preparing dishes from local seasonal ingredients. One could combine the changing of the two bit special with the changing of ingredients to create a more compelling special.