Light Bulb - PC Users

Q: How many PC users does it take to change a lightbulb?
A: Two. One to do it, but one to check the new bulb for viruses first.

Light Bulb - Joke Readers

Q: How many Jokerz joke readers does it take to change a light bulb?
A: 28. One to screw in the first one, 3 to follow the first one by screwing in the exact same bulb, 20 to screw in an almost completely similar bulb with a slight difference, 3 to complain about the lighting, 1 to explain that it was not the right type of bulb for this socket, and 1 standing by displaying the canonical collection of bulbs.

Light Bulb - Rec. Humour Posters

Q: How many rec.humour posters does it take to change a lightbulb?
A: 31. One to change the lightbulb and thirty to flame them for picking the wrong wattage. No, better make that 32 ... Captain Nitpick will want to point out that the newsgroup is rec.humor (US spelling) *not* rec.humour.