I assume this is one of those cases where if you're in the culture, you'll know which rules you're allowed to break (and when) vs if you're on the outside it's easiest to just follow all the rules all the time.

Reminds me of an episode on youtube of How The British Upper Class Live | Stacey Dooley Sleeps Over where the presenter eats her eggs "wrong", much to the dismay of her posh host who tells her (in his subtle British way) that she should "sort that out".