Other classics:
>white Australians are indigenous to Australia
>money isn't real
>5g causes cancer, usually because it's on the EM spectrum with UV light
>famous person I've never met is an alien/lizard/robot
>our food is poisoned by some kind of abstract force
>the ocean is full of petrol
>we're in a simulation
Usually they've taken some kind of thought experiment as a revelation, because it was seemingly logical but they didn't understand that the original author didn't believe the premise. IF the ocean was made of petrol, he didn't actually think it was the tool was just trying to prove a point about somthing else