The US and Britain are definitely two nations separated by a common language

[MrScorpio]

Just one example:

http://www.thefreedictionary.com/fanny

[XemaSab]

1. This makes

Fanny Hill that much better. :D

[proteus_lives]

2. Now that can lead to some painful confusion.

[Bucky]

3. I had a client once tell me of a terrible embarrassment while marketing fanny packs there in the 80s

On the other hand, they think of "shag" as a useful synonym

[Kutjara]

4. A British friend visited me a few years ago.

We were having breakfast at a cafe in Santa Monica, where he was bemoaning the ban on public smoking. "This is ridiculous. I can't start the day without a fag in my mouth," he exclaimed loudly.

[sarge43]

5. "Knock up"

as in "I'll knock you up this evening."

Bloke: To make a telephone call

Yank: To impregnate

It's a moment.

[Kutjara]

7. Actually, "knock up" in the UK is the equivalent of "wake up."

As in, "I'll knock you up at 7am."

[sarge43]

8. My mistake. Thanks for the correction.

Still it makes for a Yank double take

[Kutjara]

11. Definitely. Makes for a useful double entendre in certain circumstances as well.

;)

[sarge43]

14. Indeed. Memories........ n/t

[Tikki]

6. Well hello there, I'm randy....Hello, I am Randy...

Tikki

[KamaAina]

9. I think I'll step out back and have myself a fag

that's a "cigarette" to you bloody Yanks. :P

[Call Me Wesley]

10. Smoking a fag I rolled from my baccy, being pissed,

walking on the pavement, smelling the petrol as the trolly runs by, what a pain in the arse. I wonder if there's anything good on the telly tonight. Oh, American Idol! Bloody hell! Blow me!

[Kutjara]

12. The one I've found causes the most confusion is "half."

We Brits say "half two" when we mean 2:30. I had to modify this habit when I came to the States. I'd say "half four" and people would look at me blankly, then say, "so what's that, 2?" as if I was setting them a math problem.

[Skittles]

13. I grew up in both countries

yes INDEED

[pokerfan]

15. I've spent some time over there

London and Coventry mostly. It's not too bad unless you run into some Cockney rhyming slang, which I never did. From the first episode of Band of Brothers:

Hoobler: Holy shit!
Brit: Nah, it's alright mate, we're Tommies not Boche.
Hoobler: Is all this real?
Brit: Yeah, yeah. Well some of it's from the Germans something these toes knocked up. For you lads actually, so you can get your mince pies on some of this Jerry clobber, if you know what I mean?
Hoobler: Not really. Hey mate, you got a Luger? I'm dying to get my hands on a real Luger.
Brit: Yeah, go on then, quick butchers, yeah?
Hoobler: Boy she sure is a doozy.
Brit: Yeah it's pukka innit?
Hoobler: What?
Brit: Hey?
Hoobler (walking away): Hey Petty!
Brit: Here, mate! You're having a bath if you think you're half-inching that.
Hoobler: Oh yeah, sorry. Well good luck.
Brit: You too mate.

[LeftishBrit]

16. The American song 'Hallelujah I'm a Bum' has never quite taken on here...

One of my funnier experiences on DU was being on a thread where one poster disagreed with the rest of us on how certain terms should be used, and ended up telling us, 'You all deserve to be bonked with the dictionary!' In British English, 'bonk' has a meaning that I don't think he intended!

[Lionel Mandrake]

17. "Subway to Underground"

That's what the sign said in London. Being American, I had no idea what it meant.

A little research revealed the following:

American "subway" = British "underground"

British "subway" = American "pedestrian tunnel"

[Odin2005]

18. Apparently in the UK "mad" is only used to mean "crazy", never to mean "angry".

That could cause some trouble.

Oh, and why the F do the Brits call a stroller a "pram"? WTF does "pram" mean?

[Tuesday Afternoon]

20. short for

preambulator, IIRC.

[elleng]

19. Yes, one of the best things about us!

:sarcasm: