Four - three to cut a hole in the roof and one to change the bulb.
By holding the bulb up to the socket and waiting for the world to revolve around them EDIT: Rip inbox EDIT 2: Thanks for the gold!
One: He holds the bulb and the rest of Canada revolves around him.
No one knows, they wait for it to burn out and follow it around for twenty years.
The balls are lighter and you don't have to change shoes.
Who gives a cluck (I wonder if the moderators will censor this joke merely on the grounds that it is categorically terrible)
None! In Soviet Russia, light bulb changes you!
Your nose
One has hope in her soul and the other has soap in her hole
There's only like 7 things in life easier than cutting up fruit and one of them is farting.
It's someone who cuts hair in a library.
Tell him drinks are on the house.
17, 1 to hold the lightbulb, 1 to hold the ladder and the other 15 to drink whiskey until the roof spins
Because he was dead.
To help the firemen find the hydrants
