Two — one to change the bulb, and one to write a song about how good the old light bulb was.
or
Three. One to climb the ladder while the second kicks the ladder out from under her. And the third to say, "I knew that was too high for you dear."
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If one side has one, the other side has to get one. Once launched, they cannot be recalled. When they land, they screw up everything forever.
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As far away as possible.
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None: they just deny that the bulb ever went out in the first place.
or