Most women aren't thrilled when they show up to a party wearing the same dress as someone else, let alone the same dress as seven other women! But not these women -- they're performing a strange dance that creates a dizzying optical illusion. It's called Strumpfhosentanz and it is, you guessed it, a German dance. It translates roughly to "sock trousers dance" and it's a tradition of dancers with matching and coordinated outfits performing relatively simple dance moves to create these effects. There's actually a science behind it, as Scientific American explains, our brains being "resilient to our ... efforts to connect arms and legs to each of the dancers."