Five. One to change the bulb and eleven to say they could do it faster.
or
Four. One to change the bulb and three to whine "It's too high"
or
They screw millions of bulbs every day, but when it comes to your bulbs, there's no record.
or
What's a light bulb?
or
None, sound engineers don't do lights
or
Only one. But he'll leave a big puddle of spit on the floor underneath him.
or
None. They have machines to do that now.
or
None. They just steal somebody else's light.
or
One. But the guitarist has to show him first.
or
Just one, but he/she will spend hours checking for technical problems.
or