Two — one to change the bulb, and one to write a song about how good the old light bulb was.
or
Seven. One to change it and the other six to sing about how good the old one was.
or
To log on.
or
Clerk: "Yes, sir. What size does your alligator wear?"
or
Its days were numbered.
or
He made sure his pools were clean and his lawns were mowed.
or