Ogron 1 (Doctor Who? 151)
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An Ogron once attempted to tell the joke "How do you tell the difference between an Ogron and a plank of wood?" to another Ogron. However, after the other Ogron expressed a desire to know the answer by asking the question back to him he forgot he was the one who instigated the exchange and instead asked the other Ogron for the punchline. This continued for some time. (NOTVALID: Doctor Who? 151)