For me it is the fact that our blood contains iron. I earlier used to believe the word stood for some 'organic element' since I couldn't accept we had metal flowing through our supposed carbon-based bodies, till I realized that is where the taste and smell of blood comes from.
Something that's important to note though, is that the Cat example isn't a great way to envision this phenomenon in general. Schrodinger's Cat was actually made as an argument against this interpretation, by blowing the behavior up to a macro scale, where it seemed absurd. While you can draw analogues and all that, I'd recommend against really thinking that macro scale objects are in a multitude of obviously different states at once, all the time. It's a path to some of the really kooky fake-science "quantum" stuff that get's repeated.
Like, you're never going to see a physicist argue that a person is both alive and dead in another room, because of the technical chance that they tunneled halfway through the wall.