A Broncosaurus or a Tyrannosaurus Tex.
or
A car only has one horn.
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One's a spineless, poisonous blob. The other is a form of sea life.
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Because there was no atmosphere.
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Two. One to take notes while the other screws it into the faucet.
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When it came time to pay, the skunk didn't have a scent, the deer didn't have a buck so they put the meal on the duck's bill.
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After you die, a leech stops sucking your blood.
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Because he never pays his debts.
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