Woke up in the fireplace.
or
It went back four seconds!
or
None. The darkness will cause the bulb to change by itself.
or
Humpty Trumpty wants Mexico to pay for it all.
or
Buy a deck of cards.
or
Big holes all over Australia!
or
Seven. One to install the new bulb and six to figure out what to do with the old one for the next 10,000 years.
or