This is where we chime in with a joke about Asgard, right? The poster (right) reportedly appears outside a Shanghai cinema, and was spotted by this Korean site (the translation reads: Thor in a Shanghai theater (hahahaha) How are you going to solve it?) and on China's social media platform Weibo.
While some people wouldn't be opposed to male-on-male romp and romance between Thor and Loki in Thor: The Dark World, it is (unfortunately?) not a plot point (yet). The poster is actually a fan-made, photo-shopped image — a practice that some culture lovers, both straight and gay, do for their favorite fandoms (movies, comics, books, tv shows, boy bands etc.). It's kind of the next eventual step for fan-fic or slash fiction.
For the record, here's the original, less homosexually romantic, official Thor poster: