Kids Changing a Lightbulb

Q: How many kids does it take to change a light bulb?
A: Three. One to say, "But I never turn it on!" and two to say, "But I did it last time!"

Light Bulb - American Football

Q: How many people at an American football match does it take to change a light bulb?
A: Three. One to change it and two to tip the entire contents of the ice bucket over the coach to congratulate him on a successful bulb screwing.

Light Bulb - Academics

Q: How many academics does it take to change a lightbulb?
A: None. That's what research students are for.