Depends what you want it to change into...
Because they always want to be right.
I really just want to know.
He holds the lightbulb and the world revolves around him.
They don't. They just talk about when it did work.
None. They're too afraid of the electricity.
Two. One to change it and one to yell "Ta-daa!" when he's done.
Depends...
It depends on the age.
A magi nation
He had a hollow-weenie