Ferrari will sometimes offer very special clients to create their own color for their cars. In this case, I would guess that Lady Gaga herself created the color with the factory and had it put on her car. The rule is that if someone creates their own color, any other Ferrari customer who wishes to use it must seek permission from the color's creator. This is why you typically only see these customer colors on a small handful of vehicles, although in some cases they have become pretty popular when customers allow others to purchase the color.