Excuse me, sir. You can't take pictures here.
And why not?- The flash from your camera will damage the paintings.
- What on earth are you talking about?
- Your flash. On the camera.
- The light from the flash will fade the colors on the paintings and tapestries.
- If everyone took pictures, it would damage the artwork.
- Wow. I never knew that. I'm really sorry.
- Can I take photos without the flash?
- I'm afraid not, sir.
- In order to avoid confusion with the other patrons our museum holds to a strict no-photography policy.
- Oh. I see.
- Thank you.
why not?
：男性は何かするように言われたことに対しての理由の説明を求めている。このようなことはアメリカの文化では珍しいことではない。
What on earth
："what on earth"は"what"の意味の強調表現。「一体全体なに」