Picture this: the song "Happy" has colours. When you hear it, you see everything in red and orange. The word “Sunday” tastes like strawberries. And when someone says “mud”, you suddenly feel cold. Sounds pretty wild, but this is how many people perceive the world – people with synaesthesia, a blending of the senses. What is behind this phenomenon? How does it come about? And what does it have to do with Lady Gaga? This is what this video is about!