Pathfinder RPG 2nd Ed: Critical Fumble Card Deck - Rules of Play says:
The dice can be cruel and a critical fumble can spell doom for even the hardiest adventurer. But automatically failing to attack a target, to resist the effects of a magical curse, or overcome the symptoms of a ravenous disease isn't much fun. Instead, you can add memorable flavor and additional mechanical effects to such critical fumbles, raising rich stories from the ashes of poor luck. With more than 200 unique misfortunes, the Critical Fumble Deck is sure to add a new sense of danger to the Second Edition of the Pathfinder RPG!