As told by Exene Cervenka in The Decline of Western Civilization:

"How many punks does it take to change a light bulb? Twenty...one to hold the bulb, one to turn the stool, and eighteen on the guest list."

And as long as we're on the subject:

How many Marxist-Leninists does it take to screw in a lightbulb? None--the lightbulb's own internal contradictions will inevitably bring about revolution.