But since the advent of the internet it's gone from a few people scratching their heads amusedly to millions of people around the globe simultaneously butting heads over whether a dress is blue and black or white and gold.
The latest cause for confusion arrived on Monday, after one bona fide agent of chaos (to quote Heath Ledger’s Joker) posted a video of himself with the caption, “Rabbits love getting stroked on their nose”.
Yet this innocent caption has left hundreds of thousands questioning reality.
The infuriating video is actually reminiscent of a famous optical illusion and has triggered stark debate whether the poster is indeed stroking a rabbit’s nose or a raven’s head.
Unsurprisingly, people had a lot of fun with the discussion.
@dsquintana Here's my rabbit https://t.co/KuSGNOAAQR
— New York City tourguide Stan (@New York City tourguide Stan)