"As you probably know, there used to be a lot more people in the world, but the Great Destruction killed most of them and ruined their cities. That's why there's so much junk everywhere.

"The Great Destruction happened because everyone in the world decided to blow everyone else up, at the same time, with strange poisonous bombs. In fact, some of the ruins are still poisonous.

"If I remember my history, it occurred in August 2045. That was about 150 years ago."

Ask about something else.

End the conversation.