After almost 5 years, here are a few observations that may prove helpful to both Brits and Americans.
Never tell an American you 'tooted' at someone, they will think you rude, obnoxious and very uncouth! On the other hand, if an American tells you they 'tooted' there was no vehicle involved and you may want to move a few feet from them!
In the US if you want to really throw a group of kids into confusion, tell them you left a 'parcel in the car park'!
If someone waves two fingers at you in the US resist the urge to abuse them, they are not being aggressive or rude. You however, can freely use your two fingers with Americans and they'll be none the wiser to what you really mean!
Never use the 'f' word in general conversation with an American, the nice ones will be horrified, they just don't use it as an adjective like Brits born after the 1960's often do.
Avoid all serious conversations about religion: how you view it, act upon it and attend to it, is not your own private business as it is in the UK and you may be judged.
Brits should forget the theory that if someone is wearing a cowboy hat they are either gay or part of a Bachelor Party!
In the US jeans are perfectly acceptable as smart and even work attire, as long as they're not ripped or dirty.
A purse in the US is not your wallet, it's your handbag.
If someone refers to their pants in the US, they're not discussing their underwear with you!
If an American tells you "I don't care" in response to being asked if they want to do something, they are not being rude it just means they don't mind either way. This however is infuriating to a Brit and you may have to resist the urge to slap them!
In the US don't even bother trying to ask for "Water", just tell the person with you and get them to ask for you. This word is THE most mis-understood pronunciation!
In the US before you know it you will find yourself telling all and sundry to "have a nice day", don't even try to resist it's futile.
Don't be insulted when a US man calls you Ma'am (if you're a woman of course). He's not taking the pee, he doesn't think you're the Queen, he's just being polite.
In the US never eat Calf Fries, you'll thank me for this! If in the UK never eat Haggis for similar reasons.
If you're in the US and ask for Tea it WILL be iced. If you're in the UK and ask for Tea, it WILL be hot!
Don't be surprised to see TV adverts for Viagra in the US. In the UK be prepared for alot more nudity and swearing on TV, especially after the 9pm watershed.
If you're in the US and don't want to pay for a cup of ice and very little drink, ask for 'easy ice'. Also beware of the dreaded ice slide, where it all suddenly slides and the drink goes down your front, I have been a victim of this many times. In the UK if you don't ask for ice, your drink will come without any at all.
A yard is a garden, a garden is where you just grow produce in the US.
The UK has a strong drinking culture, the US does not, this could cause discomfort on both sides. Most Brits are not alcoholics, despite evidence that may be seen to the contrary. But I would advise Americans against drinking competitions with a Brit, you'll lose!
In the US a Mars Bar is a Snickers and a Milky Way is a Mars Bar, in the UK the reverse applies - confused?!
Don't be surprised if whilst in the UK you never see a Pickup.
In the US get used to being asked if you're an Aussie, try not be insulted or get mad!
In the UK don't ask for a restroom, you'll just get a blank look, ask for a loo. The reverse applies here!
If you're a Brit you will need to talk more slowly to be completely understood and misunderstandings will happen. Be aware the American may be too polite to ask you to explain yourself, so these can quickly escalate!
Americans don't do sarcasm, Brits overdo it. Everyone needs to beware of this important cultural difference in the interests of the 'special relationship'!
Americans are highly patriotic, Brits are not.
Americans love football, Brits worship football, but neither understands the others game!
Americans generally have a positive outlook, Brits can be very 'woe is me and the world in general'.
Indian = Native American in the US and Asian Indian in the UK.
In the mid-west US most people will say "hello" as they pass someone. In the UK everyone tends to ignore everyone they don't actually know. This can be disconcerting for both!
It's not uncommon for a rurally based American to say they either know or are related to someone in the UK and wonder if you might know them. Be polite, don't burst out laughing, they just don't understand there are 60+ million Brits in an area the size of one average state!
When in the UK make sure you eat a 'Bacon Butty', you'll thank me!
Unless you're a very confident driver in the US used to big city traffic, I would strongly advise against driving in the UK. Read up on roundabouts before you get there and be prepared for road rage aimed at you!
Brits and Americans both love to discuss the weather.
We are two nations divided by much more than a common language!