A crane.
or
"Let me see your birth certificate".
or
None, because people who glow in the dark don't need light bulbs.
Note: Topical to the Chernobyl Reactor disaster of 1984.
or
To see how long he slept.
or
Three: One to screw it in, and two to talk about how much better it is than with a man.
or
Because an undocumented worker has been living on his head for the past 2 decades!
or