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
I don't know. I didn't think sheep could knit
or
So he gave me a kite.
or
One has claws at the end of its paws and one has a pause at the end of its clause
or
At the hickory dickory dock.
or