Confirming the social import of relations between men, we are told that close same-sex relations should automatically—naturally, even—give rise to speculation, if not suspicion.
Again the idea of close bonds of same-sex comes up in the agrument for why observers inside the show, and viewers of the show for that matter, jump to assume the pair is a couple. This speculation comes up several key times during the episode "The Hound of the Baskervilles" where newly introduced characters assume that Sherlock and John's relationship is a romantic or sexual one. This GIF comes from the scene preceeding where the inn worker assumes that the pair are a couple. This particular pull out shows the pair together approaching the inn.