Because the teacher said it was a piece of cake!
or
It'll come back to me.
or
A pork chop.
or
They screw millions of bulbs every day, but when it comes to your bulbs, there's no record.
or
Because pepper makes them sneeze
or
1,000,001: One to change the bulb and 1,000,000 to rebuild civilization to the point where they need light bulbs again.
or