Does it have to be a light bulb? 'Cause I had this other idea...
One, AND IT'S NOT FUNNY!
Because he changed the light bulb before it was cool
Two, one to hold the bulb and one to rotate the universe.
N! One to change the light bulb, and n-1 to display stereotypical behavioral traits of X!
He finishes her drink EDIT: Apparently this is Conan's joke, so all credit goes to him. I just heard it from a friend of mine and I had no idea.
HULK'S MASH! no idea where she picked it up from, but it made me chuckle
CGI Friday's