Two — one to change the bulb, and one to write a song about how good the old light bulb was.
or
He wanted to make a clean getaway!
or
Shamboo!
Frankenstein: Witch can you make me a lemonade?
Witch: Poof you are a lemonade!
or
Because he wanted to draw the curtains!
or
Five: One to change the bulb and four to pull the ladder out from under him/her.
or
The owner got tired of the (w)hole business!
or