VTam, I know exactly what you mean. Am back in the US now & trying to remember to say "cellphone" instead of "mobile", "gah-RAHJH" (rhymes with "barrage" instead of "GAER-ej" (rhymes with "carriage"), "bathroom" instead of "loo", "vest" instead of "waistcoat", "sidewalk" instead of "pavement", "back yard" instead of "back garden","thank you" instead of "ta", etc.

I can get away with saying "trousers" instead of "pants", 'cos even though people rarely say "trousers" here, they do understand what it means...

More examples, and a parody what I wrote about US English vs UK English (tto "My Favorite Things" called "Don't Know the Words for My Favo(u)rite Things") here on the thread BS: English To English Dictionary

Also, "Keep your pecker up!" has a rather racier meaning in the US than in England, where your "pecker" is your nose... and you had better refer to that little bag you carry on a belt around your waist/hips as a "bum bag" in the UK, unless you want to get everyone laughing nervously.

Although, for the most part, it seems to me there are WAY more "innocent"(?) words in the UK that have a second, racy meaning than there are in the US: "knob", "baps" (too tired to think of more at the moment, but there are LOADS).

Even the way people swear is different; the first time I heard my (English) husband swear ("bastard!"), I looked to see who he meant -- in the US we use it as an adjective rather than a simple exclamation. Nor do we tend to exclaim "shite!" (unless you delete the "e" on the end) or "bollocks!"

Then there's the UK's two-finger salute, which would get you a blank look (if it was even noticed) in the US. Likewise, UK-ers don't seem to "flip you the bird".

I find this stuff fascinating, but I'll stop here.