Three:
One to write the light bulb removal program,
one to write the light bulb insertion program, and
one to act as a light bulb administrator to make sure nobody else tries to change the light bulb at the same time.
or
It's what the queen says after she burps.
or
One, but she'll be on the phone for five hours telling all her friends about it.
or
The owner got tired of the (w)hole business!
or
Hey, bud!
or
At the hickory dickory dock.
or