When Katy Perry gets dressed, her goal is to turn as many heads as possible. Like her BFF Rihanna, this is usually achieved by going with the wildest attire available. That mean cupcake boobs, see-through dresses, and barely-there bikinis. In honor of the singing superstar's 27th birthday, we've assembled a gallery of the provocative outfits that will be the reason the California girl really goes down in pop history—in our eyes, at least. Keep clicking for all of Katy Perry's Most Risqué Looks.