Sometimes overlooked because it's a non-sports issue that came in a sports wax pack (1963 Fleer Football Cards) is the 54-card set known as Goofy Gags. There are a few on ebay now, and a lot of 24 or so recently sold on ebay. I have been looking for one particular one for a long time and I have many to trade!
The wrapper, display box, and an unopened pack can be seen here. You can see on the front of the wrapper it says: "Extra! Free Goofy Gag Card" (and there is a similar phrase on the front of the display box):