Ooooo, I thought of another one. “I’m not bothered” to mean “Either choice is fine with me” or “I don’t care.” Sample conversation:
Waitress: Do you want soup or salad with your meal?
RickQ: I’m not bothered. (He doesn’t intend to eat either one)
Waitress: Huh?
Me: Salad, please. (I’ll eat it.)
Me: (after waitress has gone) Sweetie, to us, you just said you are not annoyed by salad.
One more: “I can’t be arsed” to mean “I don’t feel like it.” I really like this one and use it all the time.
White coffee = coffee with cream/whitener.
Bonnet = hood (of a car)
motorway = freeway/Interstate
fine weather = constant driving rain 
corguettes = zucchini
mangetout = snow peas
aubergine = eggplant
coriander = cilantro
“American style” = any food that does not bear the slightest resemblance to anything sold in America
And another translation of Francesca’s prose:
Several of us chappies were waiting politely in that frightfully useful place that sells alcohol and suchlike. A female was taking absolutely ages to pay - can you believe it, she actually had one of those chequebook thingies! I always put it on the account, don’t you know.
Anyway, where was I? Oh yes, just then some frightful man barged in, without even an excuse-me. Apparently he wanted some ciggies, although I swear I couldn’t understand a word he said. Most uncouth.
I gave him a piece of my mind, I can tell you!
Unfortunately he began swearing in a typically lower-class fashion. Of course I’ve heard all that sort of thing before, but some well-dressed office worker got jolly upset. Well I could see there might be a spot of bother, so I left in a dignified way.
With respect to Harry Potter… Canada got the original British version rather than the US translation of the film. I was very happy to see that. However, typically for Canada, we got a mix of British and US merchandise: ‘Philosopher’s Stone’ books but ‘Sorcerers Stone’ calendars. I think they eventually went around the problem by branding everything simply as ‘Harry Potter’.