A little over a decade after the release of the original iPhone, it seems we have arrived at some basic grounds rules for phone use in movie theaters: calls are verboten, texting is a major offense, and checking your screen in anything but the most surreptitious manner is frowned upon. But what about when watching a movie at home with others? I’ve found that the proper protocol here has remained largely unspoken—a mistake if we, as a society, want to remain on the same page.