It might be easier to advertise in ancient Greek than to try to speak to kids in their own language. For starters, kids have more than one language of their own. The huge influence of mobile phones and webchat, as well as international music trends such as hip-hop, the cults of TV and the power of role models, have given older children more than one vocabulary and lots of different ways of speaking.
A few nuggets of kidspeak have become famous. Vicky Pollard, the teenage character from the sketch show Little Britain, has made the expression "yeah, but no, but yeah" commonplace. Meanwhile, the comedian Catherine Tate's TV character Lauren - the schoolgirl-with-attitude saying "am I bothered?" and "whatever" - is now among the top-selling ringtones.
But it's unlikely any teenager would use the Oxford English spelling.
"Bovad" or "wateva" is a more acceptable, text-friendly shortcut.
Abbreviation is the name of the game. "Emo" is short for emotionally different, "lol" can mean lots of love or laugh out loud and "rofl", rolling on the floor laughing. Not only do kids now talk in abbreviated words, they have even been known to write exam papers using text shortcuts.
Around 33 per cent of seven- to 11-year- olds and 77 per cent of 12- to 16-year-olds own a mobile phone, according to research by the youth specialist research company Carrick James Market Research. The same research shows that, on average, a seven- to 16-year-old sends 24 text messages a week. So it's not surprising textspeak has become part of the vocabulary. As well as phrases such as "g2g" (got to go) or "brb" (be right back), there are lots of variations on the theme of a smiley face - : ) - using keyboard characters to say more than words can say. (See transl8it.com for translations.)
While some of these words and phrases are mainstream, urban youth speak is more cutting-edge. The communications agency Contenda specialises in reaching a youth audience, and recently worked on a guerrilla marketing campaign for Disney.
Contenda's managing director, Joe Pidgeon, explains where urban youth speak comes from: "The phenomenal growth of the urban music industry both in the UK and globally has homogenised Jamaican patois, US hip-hop slang and cockney rhyming into an all-new London urban slang used in today's playgrounds."
So, "you're late" means that you're behind the times, "messy" means very good, "kotching" translates as chilling out at home. "My yoot" - from Jamaican patois - is anyone younger than yourself. A "hotty" is a fit girl. If "you're murking me", you're disparaging me, and if I'm "rolling deep", I'm hanging out with all my mates.
Some of this urban teen speak is easier to unravel. "Seen" means I see, "North-Weezee" is North-West London and "whagwan" means what's going on. Other expressions, such as "missing" for drunk or "wha' blow?", meaning "what's been happening?", are a little more impenetrable.
Dubit is a research and communications agency specialising in the youth market. As well as doing work for the likes of Tizer (through 23red), it also owns the popular teen website dubit.co.uk. Dubit's managing director, Robin Hilton, explains that, although not all young teenagers use much urban slang, it is aspirational. "The urban gangster cult is fairly cool ... young people pick it up from songs, they watch MTV and pick up words."
Some of the more well-used teen words include "yes" instead of hi, "sick" (cool), "well" (very), "innit" (I agree), "bean" (person), "wicked", "like" and "cool" (some things don't change). Some words mean different things to different people. A chav can be a violent person, someone from a council house or, in its original, it simply meant boy.
Other words come in and out, according to who is using them. So, "minging", defined in the Dictionary of Playground Slang as of 70s origin, meaning smelly, ugly or extremely drunk, was more popular when Jade Goody was in the Big Brother house.
Kids are now more likely to pick up the lingo of the gangster pop star 50 Cent.
Nevertheless, "minger" or "munter" has wormed its way into the vocab of plenty of tweenies. They often use it with hand signals for emphasis.
The long-winded insult "loser, loser, double loser, minger, your mother works at McDonald's" is signed as an "L" with the thumb and forefinger, then "M" with two thumbs and forefingers, followed by the McDonald's "m", with three middle fingers down. For the older kids, all this hand-waving can look a bit uncool.
The nature of teenspeak is that it is constantly changing, so efforts to pin it down are always somewhat dubious. The BBC website has a "lexicon of teenspeak", published last summer.
Entries include "standard" (it goes without saying) and "rago" (OK).
Also: "'Bum' - to enjoy ... there are levels of bummage - to really like something is to 'bum it blue', but 'he bummed it black' means he used to like it but has since gone off it."
Some advertisers, of course, have more reason than others to want to be aware of the latest playground slang. According to TGI, more than 80 per cent of 11- to 17-year-olds own a games console. Neil Hourston, the planning director at TBWA\London, works on the PlayStation business. Although he's quick to point out the dangers of trying to keep in touch with such a rapidly changing scene as kidspeak, he does keep his ear to the ground.
As well as text and urban speak, kids have dreamt up other ways of communicating.
"There's an online language called 'leet speak'," Hourston says. "It's keyboard-based and can't be spoken or written - you choose numbers or symbols that look like the letters." (See ryanross.net/leet.)
Another language is backslang. This is a code that takes the original spelling of words and adds extra letters and syllables for effect or to disguise the real meaning. The rap lyric "fo' shizzle my nizzle" (meaning "for sure") is an example. Let any advertiser wanting to speak in teen beware.