Ace - If something is ace it is awesome. I used to hear it a lot in Liverpool. Kids thought all cool stuff was ace, or brill.
Arse - This is a word that doesn't seem to exist in America. It basically means the same as ass, but is much ruder. It is used in phrases like "pain in the arse" (a nuisance) or I "can't be arsed" (I can't be bothered) or you might hear something was "a half arsed attempt" meaning that it was not done properly.
Bladdered - This rather ugly expression is another way of saying you are drunk. The link is fairly apparent I feel!
Bloody - One of the most useful swear words in English. Mostly used as an exclamation of surprise i.e. "bloody hell" or "bloody nora". Something may be "bloody marvellous" or "bloody awful". It is also used to emphasise almost anything, "you're bloody mad", "not bloody likely" and can also be used in the middle of other words to emphasise them. E.g. "Abso-bloody-lutely"! Americans should avoid saying "bloody" as they sound silly.
Bob's your uncle - This is a well used phrase. It is added to the end of sentences a bit like and that's it! For example if you are telling someone how to make that fabulous banoffee pie you just served them, you would tell them to boil the condensed milk for three hours, spread it onto a basic cheesecake base, slice bananas on top, add some whipped double cream, another layer of banana and Bob's your uncle!
Bodge - We bodge things all the time here. I'm sure you do too! To do a bodge job means to do a quick and dirty. Make it look good for the next day or two and if it falls down after that - hey well we only bodged it! Applies to building, DIY, programming and most other things.
Bollocks - This is a great English word with many excellent uses. Technically speaking it means testicles but is typically used to describe something that is no good (that's bollocks) or that someone is talking rubbish (he's talking bollocks). Surprisingly it is also used in a positive manner to describe something that is the best, in which case you would describe it as being "the dog's bollocks". Englishmen who live in America take great delight in ordering specialised registration plates for their cars using the letters B.O.L.L.O.X. Good eh?
Botch - There are two expressions here - to botch something up or to do a botch job. They both mean that the work done was not of a high standard or was a clumsy patch. My Dad used to always tell me that workmen had botched it up and that he should have done the work properly himself.
Bugger - This is another fairly unique word with no real American equivalent. Like bloody it has many uses apart from the obvious dictionary one pertaining to rather unusual sexual habits. My father was always shouting "bugger" when he was working in the garage or garden. Usually when he hit his thumb or dropped a nail or lost something. Today we might use the sh** or the f*** words but bugger is still as common. The fuller version of this would be "bugger it". It can also be used to tell someone to get lost (bugger off), or to admit defeat (we're buggered) or if you were tired or exhausted you would be buggered. You can also call someone a bugger. When I won £10 on the lottery my mate called me a "lucky bugger".
Cheeky - "Eee you cheeky monkey" was what my mother said to me all the time when I was a kid. Cheeky means you are flippant, have too much lip or are a bit of a smart arse! Generally you are considered to be a bit cheeky if you have an answer for everything and always have the last word. My licence plate on my MX5 (Miata in American) was CHEEKY, which most Texans thought was something to do with bottoms - wrong!!
Cheerio - Not a breakfast cereal. Just a friendly way of saying goodbye. Or in the north "tara" which is pronounced sort of like "churar".
Cheers - This word is obviously used when drinking with friends. However, it also has other colloquial meanings. For example when saying goodbye you could say "cheers", or "cheers then". It also means thank you. Americans could use it in English pubs, but should avoid the other situations as it sounds wrong with an American accent. Sorry!
Cheesed off - This is a polite way of saying you are pissed off with something.
Chuffed - You would be chuffed to bits if you were really pleased about something.
Cock up - A cock up means you have made a mistake. It has nothing to do with parts of the male body.
Codswallop - Another one I heard a lot as a kid - usually when I was making up excuses for how the window got broken or why my dinner was found behind the sofa. My Dad would tell me I was talking a load of codswallop. American kids might be talking baloney under the same circumstances.
Cor - You'll often hear a Brit say "cor"! It is another one of those expressions of surprise that we seem to have so many of. It will sometimes be lengthened to "cor blimey" or "cor love a duck", depending on where you are. "Cor blimey" is a variation of "Gawd Blimey" or "Gor Blimey". They are all a corruption of the oath "God Blind Me".
Daft - My Dad used to call me a daft 'apeth which is short for a daft half penny (in old money). It basically means stupid.
Dear - If something is dear it means it is expensive. I thought Texan insurance was dear.
DIY - This is short for do it yourself and applies not just to the DIY stores but also to anything that you need to do yourself. For example, if we get really bad service in a restaurant (oh, you noticed!) then we might ask the waiter if it is a DIY restaurant - just to wind them up.
Dog's bollocks - You would say that something really fantastic was the dog's bollocks. Comes from the fact that a dog's bollocks are so fantastic that he can't stop licking them! Nice huh? Often shortened to just "The dog's".
Donkey's years - Someone said to me the other day that they hadn't seen me for donkey's years. It means they hadn't seen me for ages.
Flog - To Flog something is to sell it. It also means to beat something with a whip, but when your wife tells you she flogged the old TV it is more likely she has sold it than beaten it (hopefully!).
Fluke - If something great happened to you by chance that would be a fluke. When I was a kid my Mum lost her engagement ring on the beach and only realised half way home. We went back to the spot and she found it in the sand. That was a fluke.
Give us a bell - This simply means call me. You often hear people use the word "us" to mean "me".
Gobsmacked - Amazed. Your gob is your mouth and if you smack your gob, it would be out of amazement.
Grub - Food. Similar to nosh. I remember my Dad calling "grub's up", when dinner was ready as a kid. A grub is also an insect larva. Not usually eaten in England. Actually is available in some Australian restaurants!
Gutted - If someone is really upset by something they might say that they were gutted. Like when you are told that you have just failed your driving test!
Hunky-dory - My English dictionary tells me that hunky-dory means excellent. We would generally use it to mean that everything is cool and groovy, on plan, no worries and generally going well.
Jolly - You hear people use this in all sorts of ways, but basically it means very. So "jolly good" would mean very good. A common exception is where you hear people say "I should jolly well think so!" which is more to emphasise the point.
Knackered - The morning after twenty pints and the curry, you'd probably feel knackered. Another way to describe it is to say you feel shagged. Basically worn out, good for nothing, tired out, knackered.
Knock up - This means to wake someone up. Although it seems to have an altogether different meaning in the USA! At one time, in England, a chap was employed to go round the streets to wake the workers up in time to get to work. He knew where everyone lived and tapped on the bedroom windows with a long stick, and was known as a "knocker up". He also turned off the gas street lights on his rounds. Another meaning of this phrase, that is more common these days, is to make something out of odds and ends. For example my Dad knocked up a tree house for us from some planks of wood he had in the garage, or you might knock up a meal from whatever you have hanging around in the fridge.
Knuckle sandwich - If somebody offers you a knuckle sandwich you'd be best to decline the offer and leave at the next convenient moment. It isn't some British culinary delight - they're about to thump you in the face.
Naff - If something is naff, it is basically uncool. Anoraks are naff, salad cream is also naff. You could also use it to tell someone to naff off, which is a politer way of telling them to f*** off!
Nice one! - If someone does something particularly impressive you might say "nice one"! to them. It is close the Texan good job that you hear all the time.
Not my cup of tea - This is a common saying that means something is not to your liking. For example if someone asked you if you would like to go to an all night rave, they would know exactly what you meant if you told them it was not exactly your cup of tea!
Off your trolley - If someone tells you that you're off your trolley, it means you have gone raving bonkers, crazy, mad!
Pardon me - This is very amusing for Brits in America. Most kids are taught to say "pardon me" if they fart in public or at the table etc. In America it has other meanings which take us Brits a while to figure out. I thought I was surrounded by people with flatulence problems!
Pear shaped - If something has gone pear shaped it means it has become a disaster. It might be preparing a dinner party or arranging a meeting, any of these things can go completely pear shaped.
Piece of cake - I remember saying it's a piece of cake in front of one of my American friends, who then started looking around for the cake! It means it's a cinch!
Piss up - A piss up is a drinking session. A visit to the pub. There is an English expression to describe someone as disorganised which says that he/she could not organise a piss up in a brewery!
Prat - Yet another mildly insulting name for someone. In fact, this one is a bit ruder than pillock so you probably wouldn't say it in front of Grandma.
Pukka - This term has been revived recently by one of our popular young TV chefs. It means super or smashing, which of course is how he describes all his food.
Smashing - If something is smashing, it means it is terrific.
Sod's law - This is another name for Murphy's law - whatever can go wrong, will go wrong.
Splash out - If you splash out on something - it means you throw your senses out the window, get out your credit card and spend far too much money. You might splash out on a new car or even on a good meal.
Taking the mickey - See taking the piss. Variations include "taking the mick" and "taking the Michael".
All text assembled from http://www.effingpot.com/slang.shtml