Apple released iOS 5.1 and started Japanese support of Siri. Then, the Japanese personified Siri immediately.
Why does she show ass? Because Siri means ass in Japanese(Would not Steve Jobs knew it?).
You can watch other works in Togetter.
An interesting point of this is that there are images of the butler. When Japanese people personified something until now, it was a beautiful girl in many cases. However, Siri is service of only a text. Therefore women may imagine a butler.
In addition, the Japanese does a funny experiment by using Siri. For example, they say blue jokes to Siri and inspect answers [Japanese].