Looking like a tourist can cost you money and pride.
Looking like a local can open you up to even greater harassment.
Read our survivor's guide, split the difference and come away with your upper lip intact.
1. Getting around
Travel around the UK is relatively simple.
Yes, they drive on the left, but don't be daunted. Most roads are so narrow that it doesn't make any difference which side you're on.
Be prepared when driving distances of more than 20 miles.
Britain has an extensive and efficient rail network, which only ever grinds to a halt when the weather turns hot, cold, wet or dry.
Tickets are expensive but you can find cheap fares by booking eight or nine years in advance of travel.
There are warm days in the UK, but you know you're in a damp country when the merest hint of sunshine is front page news.
Britain has four seasons, and while the transitions between them can be pleasant, each is typically as wet, gray and cold as the last.
All are considered by Brits to be "ice cream weather."
Whatever the climate throws at you, be prepared for endless conversations about it.
These needn't be dull since, like Eskimos with snow, Brits have a impressive lexicon for rain.
If you hear the word "mizzle," it probably means a light shower. Or maybe a low quality Snoop Dogg track.
Don't be duped by Downton Abbey. Britain has come a long way since the days when ordinary folk were awestruck by aristocracy.
This is a modern country where all are born equal and social rewards are based on merit.
This is why few British people bothered turning up when a blue-blooded chap married his sweetheart in 2011.
It's why barely anyone noticed when she gave birth a couple of years later.
And it's also why no one batted an eyelid when his flame-haired brother got naked in Vegas.
OK, none of that is true. British people are as in thrall to their royal family as you are.
And they're willing to sell you a Wills 'n' Kate souvenir tea towel with matching oven mitts to prove it.
Britain has so many ancient attractions, it's hard to know where to start.
And if you do manage to visit all the sites of historical interest, archeologists will simply dig up the bones of another 15th-century king from under a parking lot, just to annoy you.
But since some Brits are only aware of two key dates -- a French invasion in 1066 and an England soccer World Cup victory 900 years later -- you don't need to try too hard to catch up.
Try visiting the northern city of York, where you can wallow in 2,000 years of British history in one location.
Or Bath, where you can do the same and also wallow in a nice thermal bath.
There may be coffee shops on every UK street corner, but Britain is resolutely a tea-drinking nation.
Vast lakes of insipid infusions are consumed on a daily basis.
Visitors will note the almost mandatory provision of a miniscule electric jug, or kettle, in every hotel room.
It will take four hours to boil half a cup, but for many Brits this is an essential lifeline. There isn't any crisis they believe can't be solved with a nice cup of tea, and perhaps a biscuit.
When preparing tea, there are rituals to be observed. Use boiling water and, if you must resort to tea bags, always add the milk last.
Failure to do so will result in such distress that it may take another cup of tea to calm everyone down again.
If in doubt, mimic the body language.
Even if you're fluent in English, you may experience linguistic difficulties in the UK.
Regional dialects vary extensively in the space of a few miles, resulting in bafflement even among locals.
If you can't understand what a British person is saying, it's fairly safe to assume it's either a). something about the weather (see climate above), or b). an apology.
British people love apologizing: they're sorry to trouble you, sorry they can't be more helpful, sorry about the rain and sorry about invading your country in 1762, or whenever it was.
They also love apologizing when it's not even their fault: they're sorry that you bumped into them, sorry you knocked them to the floor and sorry that you are repeatedly thwacking them over the head and telling them to stop apologizing.
Be warned though, it's contagious.
Britain's bland national diet has been revolutionized by South Asian migrants whose spicy concoctions are now firm favorites sold on every high street.
Meanwhile, pubs that once nourished customers with despondent sandwiches are now studded with Michelin stars.
But don't be fooled.
They might pretend to love fine dining, but when on the hoof, many Brits still prefer to fill their faces with offal and saturated fat.
Few journeys are made within the United Kingdom that aren't catered with sausage rolls, Cornish pasties and Scotch eggs.
Visitors troubled by the sight of greasy meat should also be warned of three words that will strike fear -- if not full-blown cardiovascular seizures -- into their hearts: Full. English. Breakfast.
Be sure to take time out from your travels to sample a few hours of British television, but seek not the polished period dramas that are easily exported to other countries.
Where British TV excels is in its celebration of the lives of ordinary, dare we say boring, citizens.
The UK's three most popular soaps focus not on the beautiful or the damned, but on normal folk engaged in humdrum tasks like buying cheese, arguing about pottery or tending to their farms.