Borg to Change Lightbulb

Q: How many Borg will it take to change a light bulb?
A: None, they just assimilate the bulb.

Punk Rockers to Change Lightbulb

Q: How many punk rockers does it take to change a light bulb?
A: Two: One to screw in the bulb and the other to smash the old one on his forehead.

Light Bulbs to Change Light Bulbs

Q: How many light bulbs does it take to change a light bulb?
A: Two, the new one and the old one