Two men are bragging about how to use their fan.
A: I can use my fan for 20 years. First I open a fourth section and use it for five years. And then, I open another fourth and use it for another five years. And I repeat the same thing two more times.
B: Oh, that's wasteful. I have a better idea. I can use it a lifetime. First I open it wide, and I hold it under my nose. And I wave my head.
