Three - one to cast the bulb into the outer darkness, and two to catch it when it falls.
or
She ran away from the ball.
or
Five. One to change the bulb and eleven to say they could do it faster.
or
Climb up a tree and act like a nut
or
Because pepper makes them sneeze
or
They screw millions of bulbs every day, but when it comes to your bulbs, there's no record.
or
It doesn't matter, they don't have any electricity any more.
or