please, just restate it for clarity?
In answer to my own analogy,
I don’t believe that there is a walrus in your biscuit tin. I do believe that there are no walruses in your biscuit tin. It’s a made-up concept and so absurd that I’d go as far as to say that I know that there are no walruses in your biscuit tin, because there’s no reason to think that there are beyond the made-up premise I invented (though of course there may be biscuits shaped like walruses.)
However, if you were to show me your biscuit tin and go “look, a walrus” then I would revise my stance. Presented with such evidence, I would then know that you have walruses in your biscuit tin, and I would decline offers to visit you for coffee.
Substitute unicorns and bogeymen for biscuit-walri as appropriate.