With this butt app you can use your phone's camera to take a photo of someone's butt and it will calculate its attractiveness from 1 to 10 with 10 being the best. It supports both men's and women's butts.
You can share your results on Google+, Facebook, WhatsApp, Viber, Gmail etc.
Regarding permissions to access SD card, they are used only to temporary store photograph which is deleted immediately after processing. Other permissions are required by ad provider. This application is made purely for your enterntainment and is safe to use. You can easily check with network monitoring tool that your privacy is not compromised.