Why? Because they're at a fashion party, of course!

Kim Kardashian, Katy Perry and a whole host of fashionistas slipped on their trendiest gear for the Kanye West show after party at Paris Fashion Week. Rather than just relying on sparkling banter, Kanye made sure his guests had fun at his party by providing them with a go-karting course. Amazing. The main man donned a helmut to pose for a couple of pics with reality star Kim Kardashian, who had also plonked the safety gear on over her perfect locks. Kim went for a nude palette wearing pale trousers with a white fur, gold cuff bracelet and Kanye's crazy-priced $6,000 shoes. We hope she steered clear of the red wine in THOSE! If you had a giant mountain of money, would you buy Kanye's $6,000 heels?

Blue-haired Katy Perry also attended the bash. The singer, wearing a sweet Pink coat and matching ankle-strap shoes, cosied up the Kanye while the pair pouted for the cameras. DJ and model Leigh Lezark rocked an edgy leather shift dress and silver capped Chanel heels.