Two. One to hold the bulb and the other to rotate the planet.
or
Five. One to screw it in and four to tell him how bitchin' he looked doing it.
or
One, but she'll be on the phone for five hours telling all her friends about it.
or
To the dock.
or
Because sometimes you can get rid of cancer.
or
Shamboo!
Frankenstein: Witch can you make me a lemonade?
Witch: Poof you are a lemonade!
or
His powder puff is on the wrong end.
or