I don't give a damn about sports, but I do love this kinda thing. In 1989, Fleer Corporation released this baseball card for Baltimore Orioles player Billy Ripken. Ooops. From Wikipedia:
Fleer subsequently rushed to correct the error, and in their haste, released versions in which the text was scrawled over with a marker, whited out with correction fluid, and also airbrushed. On the final, corrected version, Fleer obscured the offensive words with a black box (this was the version included in all factory sets). Both the original card and many of the corrected versions have become collector's items as a result. There are at least ten different variations of this card. As of February 2009 the white out version has a book value of $120.
Years later, Ripken admitted to having written the expletive on the bat; however, he claimed he did it to distinguish it as a batting practice bat, and did not intend to use it for the card. In the same letter, he expressed the opinion that Fleer was well aware of the obscenity, and not only retained but made it even clearer, hoping to benefit from the publicity the card would no doubt receive.
Modern Man has some more baseball card funnies: "12 Hilarious Old Baseball Cards" (Thanks, Vann Hall!)