A fish!
One to put in the new one, and two to sing about how good the old one was.
Probably one but you can't generalise.
One to over hype the new lightbulb and one to make sure it breaks within a year.
None. Mice can't change light-bulbs as they are mere rodents without the physical or mental ability to do so. Not to mention it's much safer for them to pilfer food in the dark.
The conga!
Lightbulb.
