During her chat with the queen today, Michelle Obama briefly and lightly put her hand on the royal back. And while this may not seem like a big deal to ordinary humans, it is a violation of strict rules of royal etiquette, which amount to: Beyond a limp handshake, keep your hands to yourself. Such breaches of protocol have caused international kerfuffles in the past, Time notes, but Michelle apparently has gotten away with it.
For the record, it should be noted that the queen started it—she briefly put her hand on Michelle's back first. Also, the first lady is not a subject of the queen, and those aforementioned kerfuffles involved Australian diplomats, who can't say the same. For her part, Queen Elizabeth did not seem all that disturbed by the touch, "though she appeared slightly surprised as she drew away," notes Time's Howard Chua-Eoan. Stay tuned for the UK etiquette police to weigh in.