None. The darkness will cause the bulb to change by itself.
or
The owner got tired of the (w)hole business!
or
His powder puff is on the wrong end.
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."
or
6: 2 to screw in the bulb and 4 to testify that it was lit from the moment they began screwing.
or
Twenty. One to hold the bulb, two to turn the ladder, and 17 to be on the guest list.
or
Sure, Dick and Bob had a bunny!
or