very simple. 1st person (Me) posts a disaster. then 2nd person posts why it cant happen, and then thry post a disaster. and so on, ad infinitum, et cetera...
Example: P1: Zombies eat Australia.
P2: Their teeth are too brittle.
Pokemon destroy New York City.
P3: Here's a shocker, buddy: They dont exist.
I'll start: Archiac dies of radiation poisoning.