What a cute card. It certainly makes you take notice!
This old card is from 1954 and has a calendar on the back. The front, as you can see, reads "There is a difference IN SOFT DRINKS TRY C & C SUPER in the Sanitary Cap Top Can."
The back of the card says, "IT'S 'SUPER' all year 'round." Then there is a calendar for the year. I assume this would have been to keep in your wallet in case you needed to check a date.
I think it is a clever little advertisement but would it be acceptable today?