Drinking, bathing, washing, swimming, etc.
or
'It's not unusual' he replied.
or
Two. One to screw it in, and one to stab the other in the back and take all the credit.
or
Silly, WASPs don't screw in a light bulb, they screw in a hot tub.
or
Just one, but he/she will spend hours checking for technical problems.
or
Only one. But he'll leave a big puddle of spit on the floor underneath him.
or