@Qpax

This picture should not be rating:safe. It's a butt in tiny booty shorts. Use a bit of common sense.

From Howto:rate:

Image ratings help users organize and search through the various levels of explicit content contained on Danbooru. It's very important to rate your uploads properly. By doing so you help ensure that searches continue to return accurate results.

Danbooru has three ratings: Rating:Safe, Rating:Questionable, and Rating:Explicit. Broadly speaking, these categories are:

• Rating:Explicit: For pornography — images containing explicit sex, gratuitously exposed genitals, or that are otherwise pornographic.
• Rating:Questionable: For images that may contain some non-explicit nudity or sexual content, but that aren't quite pornographic.
• Rating:Safe: For everything else. Note that rating:safe does not mean safe for work and may still include "sexy" images containing cleavage, panty shots, skimpy bikinis, and so on.

Do note that while Safe pictures MAY have a butt and such, that's more or less so that a picture that has only a little tiny bit won't be disqualified on principle, like post #2764761. A picture that focuses on the sexy aspects, such as this, is Questionable.