I made it. I gathered posts there because I couldn't find a tag for the topic "off_shoulder". But now I have, so I moved everything relevant over to there. What's left are some things that don't qualify under the wiki. To make this tag easier to find, I suggest a few aliases that I tried when looking for it:
exposed_shoulder
shoulder_exposed
loose_shirt_collar
one_shoulder_out (by analogy with one_breast_out)
shoulder_out

You can request an alias to fix it, or a BUR to do the same for multiple tags at once--or to let you edit it in case you made a typo or something.