I found this one on TvTropes:
http://www.fanfiction.net/s/617161/1/WhoopsDidntMeanToDo_That

It's... hilarious. What happens if, after Sakura became the Mistress of the Clow Cards, Meiling opens a book with Clow's failure cards? Hilarity Ensues!

Olny one spoiler: nearly all characters will think "Clow was an idiot". After all, the wand for he Whoops cards has a rubber duck on it. Yes.