They're both plastic and little boys turn them on.
or
He wanted to win the no-bell prize!
or
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
Two: One to screw you out of a fee, and the other to send you to a store where they ran out of bulbs weeks ago.
or