I dunno if what I saw was a movie on the book, I haven't read the book, or if it was about a myth that had the same idea as the book. But the thing I saw on monkey paws, once you have your wishes granted, you could NEVER say "I wish..." in even an off-handed manner or your wishes would all be cancelled.

Though if there were no side effects... there's only one wish I'd need granted. The one of the heart.