"%" meaning "fuckyer" and "#" of course meaning "hashtag"
Therefore, "%#" is meant to mean "Fuckyer hashtag". Meant as a response to the activity of "over-hashtagging"

Fuckyer "%", has become another growing internet phenomenon, after being proposed by a viral video. Although not officially (or possibly ever to be) recognized by the actual internet social sites, Twitter, Facebook, or Instagramit is used on, popularity seems to have pushed "%" further into the mainstream. Also, "%" can not only be used as a response to just hashtags, but also simply something that a person simply dislikes or disagrees with. However this article focuses on the "%#" aspect of the term.

Referring to women who are sexually or romantically attracted to other women. Applies to both lesbians and bisexual women, as it is only the same-sex attraction that matters, not any other attractions the women may have.

Originates from the Greek poet Sappho, a bisexual woman from the Isle of Lesbos, from which we get the term lesbian.