I agree, Faldage, that "cards as sports" is a stretch. Then you might have to include boardgames (i.e. Scrabble®, Hogwash® ;) and other games of chance (craps, roulette, etc.). why is ® printing so large all of a sudden?

But the newest connotation for wild card that can validate it's sports inclusion is the wildcard team, the wildcard playoffs (why do I want to make it one word here? is this correct or no? are both forms a matter of choice?). The wildcard team being the one with the weakest record that just sneaks into the playoff picture.

Of course, the class clown could be a wild card, too!