Barbie - Apart from being a doll, the barbie is the grill. Either coal or gas fired, it's what we cook our dinner on in the 2 days that makes up a good British summer. It's full name is the barbecue. So when we say barbie or BBQ we are talking about the cooker itself not the food. If you have people around you would call the event a BBQ as well.
Beer - Normally called bitter, this is the most popular alcoholic beverage of the UK male drinking population. It is served in pints at just under room temperature (real ales, however are served AT room temperature). Real Ales are non carbonated beers made from hops and barley.
Bevvy - If someone asks you if you want to come out for a bevvy, they are asking you to the pub for a beer. Bevvy is just short for beverage, but in this context the beverage in question is obviously of the alcoholic nature!
Biscuit - Cookie in America. Though the large home-made chocolate chip type things would also be referred to as cookies in England. We also use the word "biscuit" to mean cracker, for instance you will see "biscuits for cheese" in the supermarkets, which are assortments of crackers.
Bitter - Bitter is what we call beer. However, this is not what you call "beer" - we call that lager. Beers are the dark ales that are so popular amongst British drinkers. Served a little below room temperature, but not cold like yours.
Buns - Fruit buns are made by aunties and grandmas and often served with a cuppa. It is perfectly acceptable to say "Mmmmm, nice buns Grandma".
Butty - A butty is a sandwich. The most famous butty is the chip butty. The perfect chip butty (invented in Liverpool) consists of two fairly large slices from a large white loaf, liberally buttered, layered with chips (salt and vinegar optional) and smothered in tomato sauce.
Candyfloss - Cotton candy. The same horrible sugar based fluff that you get at fairs and carnivals. Kids love it and mums hate it.
Chip butty - We grew up on these in Liverpool. They are sandwiches made from white bread, buttered and filled with piping hot chips and tomato sauce!
Chip shop - Abbreviation for fish and chip shop. Also known as the "chippy" or "chipper" in some places.
Chips - Fries to you. Fish and chips is still a favourite in Old Blighty. Whilst government health restrictions prevent them from being served in newspaper any more, they still taste best from the bag, liberally dosed in salt and malt vinegar.
Cider - In some parts of south west England, Cider is more popular than beer. It is made from the juice of apples, allowed to ferment and is generally more alcoholic than most beers.
Crisps - Salt and vinegar, cheese and onion, beef, smoky bacon. Crisps are called chips in America.
Cuppa - Cup of Tea. Served at 4pm, sometimes with tea cakes, crumpets, biscuits or cakes. My favourite is a real cream tea which is a pot of tea with scones, clotted cream and strawberry jam. Tea is also served in bed at the weekends when you wake up, Mmmmmm!
Curry - England has more than it's fair share of Indian restaurants. Anything from a korma or a bhuna to a madras or a vindaloo are amongst the favourite curries. Curry houses are one of the few places that serve alcohol (lager) after the pubs shut. Therefore it is very popular, after your 10 pints of lager, to pop next door to the curry house for 10 more pints, some poppadoms and a good curry. This mixture is perfect for churning out the infamous "pavement pizza". Use your imagination!
Doner - Short for a doner kebab. The closest thing in the US is a gyro. Kebabs in England, whether shish (meat on a skewer) or a doner (lamb on vertical spit), are served in split pitta bread with salad. There is a whole culture difference between the clean living shopping mall gyro and the greasy doner. Whilst the gyro is available all day and all evening and enjoyed by everyone, the doner is generally sold after 11pm in England to young males, after the pubs close and after 8 or so pints of lager. Usually served with extra hot fresh chilli sauce and on greaseproof paper so the oil is funnelled back onto your trousers, it is usually enjoyed standing up.