Use the principle of Kook Neutralization. Confront them with a hollow-earther.
Cluff is against the claim made by the flat-Earthers.I don’t know how the flat-Earthers can be so confused. They are obviously wrong. The world is not flat – it’s hollow. They reject all the evidence,he said. Unlike, the flat-Earthers, the hollow-Earthers believe that our Earth is spherical but with a hollow body. Their conspiracy theories also suggest that the moon, the stars, the Sun, and other planets are all hollow bodies.