"I'm stuffed" in the U.S. means "I've had too much to eat", but apparently in Australia it means you've had sex? I was told this by a friend who repeated the phrase in an Sydney restaurant and got funny looks, but it sounds far fetched to me.
As an Aussie I'm calling "rubbish" on this one. I've only ever used, and heard, "stuffed" to mean either really full or really tired.
Not sure if this is related, but when my school group went to France, one of the guys got into trouble with "I'm full" - "Je suis plain" (the literal translation) means "I'm pregnant" with a connotation for animals instead of humans.
Something I'm curious about - how many slang terms for "drunk" do you have? Off the top of my head I can think of several terms which would be interchangeable in the phrase "Let's go get ________!" :
I know there are some you Brits use and we don't, but I can't think of them offhand
Do the rest of these translate? (And for that matter, can you use ANY verb and make it obvious? Hmmm . . . "Let's get bowdlerized." "Let's get flattened." "Let's get impeached." Yep, looks like it