You got me curious. Urbandictionary's top definition:

The male of the species, the 'chav', is often to be found lurking in braying packs close to fast food outlets or late night stores. It displays a distinctive livery with which it attempts to attract the female ('chavette') - most commonly, the Burberry-effect baseball cap (placed at a jaunty angle, sometimes partially covering the face - this is known in some cultures as 'snidey'); the 'sports' clothing (this is somewhat confusing as the chav is not renowned for its athletic abilities) and countless items of 'bling' (Chav patois meaning jewellery or other adornments). The origins of said 'bling' are various as the chav typically possesses neither a means of employment or indeed any type of education. Chavettes, meanwhile, tend to have hair in at least two colours, ill-fitting tops and white tracksuit tops (usually Kappa). Note their ornate 'love bites': tribal cicatrices around the neck, usually perpetrated by a near-toothless male known as Kev, Daz, Gaz, Baz, Tez or some other monosyllabic name.

Health and Education

Chavs can often be seen smoking - an activity which causes them to spit and cough, but only in public places (see above). They imbibe alcohol, normally in the form of cheap lager / cider normally obtained illegally. This often gives them the impression that they are 'hard' and they will thus attempt to start fights with anyone/thing smaller than them. However, upon retaliation of their prey they tend to run away.

Chavs are, believe it or not, to be found in education. Again, they tend to subsist in packs and can be seen braying and howling in the classroom, challenging even the most reasonable of requests to shut the hell up and let other people learn things. They tend to leave school before the age of sixteen, however, in order to pursue parenthood or a life of crime.

Transportation

The chavette is rarely seen driving a car. Instead, she is to be found holding up various bus passengers as she attempts to manoeuvre her outsized three-wheeled buggy onto a local bus service. She is usually en route to a supermarket or other place where she can swear at or smack her children publicly (this is the only form of discipline, usually to an extreme, ever displayed by chavs or chavettes towards their children and so it is required by law that it takes place wherever others may be gathered).

The chav can be found spending seemingly endless resources of money adding bodykits and neon striplights to his car (sometimes known as a 'chaviot'): this is normally a pre-1990 Ford Escort with 1100cc engine and XR3i stickers, a near-suicidal Vauxhall Nova (with plastic split-screen effect, or the occasional BMW coated in Hammerite. The real mystery about this is how the vehicle can move under the weight of the stereo system installed (badly) within. A large sticker usually adorns the rear (tinted) windscreen of the vehicle, proclaiming the brand of stereo equipment supposedly fitted inside. Loud, bassy music of indeterminate genre / origin will more often than not be emanating through the very loose tinted side windows.

Language

The typical Chav speaks a language which has yet to be named. It claims to have its roots in English, although this is in some doubt. Most Chav words are mercifully brief, and sentences tend to be punctuated with 'innit' or some sort of expletive. Only chavs can truly understand the language - the rest of us can only guess at the witty repartie and intellectual gems of conversation that may pass between them. If you see a young male (aged 12-35) dressed like an elderly lady's shopping trolley, you have in all likelihood just witnessed a chav. In this situation, you are permitted by common consensus to find the nearest firearm and descend upon said chav with all force.