As many as possible, and don't *ask* what they do with the old bulb.
or
Because an undocumented worker has been living on his head for the past 2 decades!
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It takes two. One to change the bulb, and the other to kick the switch.
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None: A `Real Woman' would have plenty of real men around to do it.
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Because there's no one else to wag it for him.
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Six. One to turn the bulb, one for support, and four to relate to the experience.
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In sundae school.
or