The If you truly believe in gay rights, then repost this and title the post as "Gay Rights". If you don't believe in gay rights, then just ignore this. meme has been showing up more and more on my flist. (I'd mostly been seeing it, and the backlash thereto, on friendsfriends.) The first time I saw it on my flist I didn't have a strong reaction against it, but I'm disinclined to participate in copy-and-paste memes and was very uncomfortable with the idea that my non-participation in this would trump my personal history (queer libertarian -- thus with both a personal and an ideological investment in consenting adults getting to do whatever they want provided those rights don't infringe on anyone else's rights to freedom and pursuit of happiness). I don't think anyone familiar with me/my LJ at all would interpret it as such, but that is what the meme is saying.
There are other problematics and discussions I could get into (and happily will in comments if anyone wants/brings them up) but that's the primary point I wanted to make.