Jonnie Robinson, Curator, English accents and dialects, British Library Sound Archive, writes:
These speakers talk about the special language used among show folk. The use of seemingly mysterious secret languages, such as children's codes, theatre-speak, butcher's back-slang, polari (a language that was once extremely common among the gay population of the UK) and even Cockney Rhyming Slang in its original form illustrates the need among certain groups for a means of communication that sends out a strong signal of membership to the initiated, while excluding those outside the target group. Show folk with their strong historical links to the gypsy and traveller community often use words or expressions of Romany origin to communicate among themselves as confirmed here.
The Romany word chavi means child, but as Rebecca explains here it has more recently been adopted across the country to refer to young people who typically dress in tracksuit trousers, hooded tops, and checked baseball caps and are generally regarded with disapproval due to their perceived boisterous, disruptive behaviour and self-assured manner. In fact the word chav has been in use for some time in parts of the UK - most notably in the Medway towns in Kent - as a derogatory term for gypsy and as is quite common with terms of disapproval its meaning has been extended such that it's now more often applied to another group that's viewed with equal suspicion. The word has recently achieved national recognition in a remarkably short space of time, probably due to media interest and the emergence of a number of popular websites devoted to such light-hearted pursuits as 'celebrity chav-spotting'.
The other words cited here are also of Romany origin: kushti means good, fine or nice; nanti means don't, no or not; dik in the phrase dik at that means look; jaul means go and pogger as in pogger him means beat or break. As with the word chav, some of these words have been adopted into more mainstream slang - nanti is widely used in polari, for instance, and kushti, often anglicised in print to cushty is extremely widely used and has indeed been popularised by its use by such well-known figures as the character Del Boy Trotter in the BBC sit-com Only Fools and Horses and the celebrity chef, Jamie Oliver. It's not surprising, however, that words used among the traveller community have been absorbed into regional and national slang, as by definition they have a roaming presence across the UK and thus take their language with them wherever they go.
The grammar of several English dialects exhibits a number of non-standard features. The construction here if we was in company and, like, we was in a group with ourselves is unmarked for person. In many dialects across the UK speakers mark the past tense of to be by saying I was, you was, he, she and it was, we was and they was, whereas speakers of other dialects differentiate by using you were and we and they were. The non-standard pattern is in fact more regular and indeed mirrors the model for every other verb in English - consider I played, you played, I went, you went and so on. Finally the use of do in the statement it's just the way I do speak is a traditional feature of speech in parts of Wales and the English West Country. It's perhaps no longer as common among younger speakers, although it rather accurately expresses the idea of repeated or habitual action - something someone does on a regular basis.