Why does the man want to buy a shirt?

W: Can I help you?
M: I’ d like to buy a fine shirt as a birthday present for my father.
W: What size shirt does he wear? Is it a Size 40?
M: Let me see. I’ m afraid that’ s not big enough. He is tall and fat.
W: Here are some bigger size shirts. How about these white ones?
M: No, so many people wear white shirts. And my father doesn’ t like black.
W: What about this one?
M: Oh, good.  My father likes blue.  I’ll take this blue one.