A survey by Penguin books of 1,000 seven to 14-year-olds reveals that cool is the most popular "in" word among British schoolchildren. But anyone wanting to be mesmeric (that's really cool) will need to know the alternatives such as crovey, sick and bodashes.
Among the dozens of words uncovered by the survey are some from TV programmes and adverts such as doh! from The Simpsons, Ali G's boyakasha and whazzup from the Budweiser commercial.
If you want to dis (insult) someone you also have a choice - baphead, a dingbat or a gonk. And if you want to be more specific there's facety (rude), butters (ugly) or even a biffin' cruiser (an arrogant person).
However, even masters of kids' lingo cannot afford to rest on their laurels. "Especially among children, terms go in and out of fashion. Parents should be warned: a word that was once cool can very often lose its pace on the hotlist. Naff is well, naff," says Nigel Wilcockson, editor of the New Compact Penguin English Dictionary. Fab, lush and awesome are also now well out.
Although groovy still makes the cool list there are signs it may be on the way out. One Essex schoolboy told researchers that "groovy is a girl's way of saying cool".
There are also regional variations. In Bedfordshire, something rubbish is poop. But in Sussex it would be pants and in Essex, crued.
Mr Wilcockson says that children are some of the great language innovators. "They love to play with language and their new words can have many different meanings. At one school greb means skateboarder or weirdo - obviously one and the same thing in some people's eyes. Safe can mean thanks, but also trustworthy, as in 'you're safe'."
So what are the chances of seeing words such as lairy (feisty) and trev (someone who wears designer clothes) in the dictionary?
"Some - like pants, manky and dis - are there already," says Wilcockson. "It depends which words we believe will remain in the language and which will just stay in the playground. And that's for us boffs to decide."
AN ADULT'S GUIDE
If it's COOL it's also...
If it's rubbish...
And some dissin' (insults)
Talk to the hand (because the face ain't listening)