Science Fiction Writers to Change Lightbulb

Q: How many science fiction writers does it take to change a light bulb?
A: Two. One to screw in the light bulb, and one to say, "In 1876, Jules Verne had the first intimations that electrostatic power was a viable energy alternative. Hitherto, the only sources ..."

Heavy Metal Fans to Change Lightbulb

Q: How many heavy metal fans does it take to change a light bulb?
A: Three. One to change it and two to say "Excelleeeeeent !"

Light Bulb - Chess Grandmasters

Q: How many chess grandmasters does it take to change a lightbulb?
A: 21. One to have the idea, and a whole load more to do all the analysis.