When you are eating a watermelon.
or
They both whine alot!
or
50. One to screw in the light bulb and the remaining 49 to guard him .
or
It ran out of juice!
or
Twister!
or
So he gave me a kite.
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