Jack Applin sends this in. “Bob states that all the sides and angles are equal, which is true for a (regular) octagon. Yes, and … ? Is it a gag about the word “side”, that there’s no need to get to the other side, because all sides are equal?“

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Unless someone can think of a reason why it might be meaningful, let’s assume that “⦣BDC” is simply a typo for “⦣BCD“.

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Here are a couple of octagons that are not regular. After someone explains what the joke is, we can consider whether the joke would apply to these octagons.