The internet loves a good optical illusion. Remember the dress? Or the case of the missing legs? This time around everyone’s obsessing over “a colour you’ve probably never seen before.” It all started with a video posted by TikTok user Kate Bacon, who graduated with a bachelors degree in integrative physiology last year, and begins most of her videos with “What’s shakin’ bacon!” “I’m going to show you a colour that you’ve probably never seen before,” Bacon says in the video. “It’s called true cyan and most TVs and monitors aren’t capable of producing this pigment.” All you have to do is stare at a white dot in the centre of a red circle on a blue background for about 30 seconds and the luminous, elusive true cyan will appear. Bacon’s not the first to share this optical illusion.