even a blind squirrel can find a nut once in a while, a stopped clock is right twice a day (even a usually clumsy or foolish person can be right sometimes, even if it is just by chance; even an unlucky person can be lucky once in a while)
köken: vak (“blind”) + tyúk (“hen”) + is (“even”) + talál (“to find”) + szem (“grain”) + -et (accusative suffix), literally “even a blind hen finds grain”