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."
or
Someone stepped on its mouse.
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Take regular water and just boil the hell out of it.
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Put it in a glass with some ice cream and root beer.
or
1,000,001: One to change the bulb and 1,000,000 to rebuild civilization to the point where they need light bulbs again.
or