Challenge
What's one thing you can say to correct someone that believes the earth is flat?
Let's be real here. The whole concept that the Earth is flat is utter bullshit, and people who actually believe this are idiots. We need to do some serious re-education in this country. Stand up and defend the truth!
Simple. Logic.
How can you keep walking without falling off the face of the Earth? Simple. The Earth doesn't have a face.