If you measure something and then I measure what you measured, we could disagree about the measurement yet both be correct.

Eugene Wigner proposed this in 1961 as part of a thought experiment called Wigner’s Friend and it has now been proven to be true.

So does this mean you could be eating a bag of cheese and onion crisps yet I could 'measure' that you're eating a bag of smokey bacon crisps and we'd both be correct? Well, not really. This all takes place at the quantum level and your choice of crisp flavours remains safely agreeable.

Mind-bending stuff though.