Derrida viewed laughter as a kind of aporia, that he related to an undecidability which he tied to fiction. This paper claims that such undecidability conduces to some jokes. At times this undecidability empowers the joke to join credibility and deliciousness. More interesting and more aporetic is the mode that undecidability conduces to jokes that spotlight their textual status (e.g. some meta-jokes) and those that impact inscrutability.