I’m a cultural Anglophile. If it a cast member of a movie or TV show has a British accent or a book is set in the UK, it must be high culture.
There are a lot of differences between American English vs. British English: some I’ve known for years: e.g., pissed (drunk); flat (apartment), boot (car trunk), bonnet (car hood), lift (elevator). With the help of Chef Google, I have even figured out foods, like saveloy (a spicy sausage) and bubble and squeak (a cabbage dish). I can sometimes manage to decode Cockney rhyming slang (trouble and strife = wife).
But there are two Britishisms which are either new or I’ve only recently become aware of.
One is a strange grammatical usage, saying “I was sat” instead of “I was sitting.” Example: “He was sat in the chair reading a book.” It just sounds “wrong” to me. It wasn’t as if an usher had come in and sat the person in the chair.
The other is more humorous. I became aware of it when a character on a show mentioned buying a pot plant as a gift. My first thought was, “How interesting. They sell marijuana as house plants in London.” Then I realized it wasn’t a pot plant but a potted plant (and not in the sense of drunk).
Anyone have other examples that have puzzled you?