There are some American words that may never make it over the Pond, such is their shock value. As many Brits know, a "fanny pack" in the USA is merely a bum-bag, since "fanny" refers to the derriere and not the um, front. The phrase still causes a mild frisson in Brits when said in real life and not just on the telly though. In my years of writing about British and American language and customs, "Don't say fanny" is probably my first instruction to Americans visiting the UK.
"Fanny" isn't the only American word that can render a Brit gob smacked though:
Army brat - I remember being at a party years ago and meeting a guy who had lived all over the world as a child. To my horror, my American husband jumped in with "Oh, an army brat?", to which the other guy simply said "Yes". I can now confirm that it's almost a term of endearment rather than the insult I first imagined.
Feeling one's oats - It must be because of the sexual connotations in "sowing one's wild oats", but this phrase always makes me freeze on the spot. In the USA it simply means to feel exuberant or be in high spirits, and alludes to the increased energy horses experience after feeding. When women walk around with it as a t-shirt slogan however, Brits can be forgiven for jumping to certain conclusions in my opinion.
Nipple - although it has the same anatomical meaning on both sides of the Pond, it also means the teat of a baby's bottle in the USA. So there I was, feeding my baby and minding my own business, when the mother on the park bench next to me asked what kind of nipple the baby preferred! (Unfortunately, I can't remember my response but I'm sure it confused the heck out of her.)
Randy - We all know that there are Americans named Randy, but it still causes a few stifled giggles when we actually meet one in person. What makes the whole situation even sillier is that the adjective "randy" doesn't really mean anything in the USA, (they say "horny"), so no one understands our nervous titters. Incidentally, females can also have this name although it's often spelt "Randee".
Shag - When the Austin Powers movies first came out, Americans were saying "shagadelic" with gay abandon, not knowing what it meant in the movie. Even worse though, you can come across pillars of the community talking about "shagging balls" or "shagging flies" when discussing baseball. This mind-boggling phrase simply refers to the act of catching fly balls in the outfield, usually in batting practice. The Wiki explanation however, does nothing to improve matters - "although shagging baseballs is not considered to be dangerous, several freak injuries have occurred as a result of engaging in it. In 1943, just one season after collecting his 3,000th hit, Paul Warner accidentally gashed his foot while shagging a fly ball in a game against the Pittsburgh Pirates." I'm tempted to say "serves him right."
Towhead - The first time an American referred to my very blond son as a "little towhead" I was taken aback, especially since he was on best behavior at the time. No insult intended though. "Tow" is the fibre in flax, hemp and jute, and "towhead" comes from the very light colour of the flax variety.
This post is adapted from a chapter in the author's book, "Rules, Britannia; An Insider's Guide to Life in the United Kingdom", 2006, St. Martin's Press.