Just two, but they'd have to be really small.
A: Just one but he wants to do it thirty-two times and when he's done everyone thinks that his last lightbulb was much better.
Q: How many Canadians does it take to change a lightbulb
Trick Question. They only think they can reach that high.
Three. 1 to screw it in and 2 to talk about how much better Neil Peart could've done it
It doesn't have windows.
Scares their dogs.