Sket is a new film about girl gangs. Sket means the same as ho or whore. The film maker contacted former gang members in south London to help make sure the language in the film was authentic and completely up to date.
Examples of slang used by this group include stralley, tool, or bucky, all words for a gun. Yeah wassup wagwan means 'hi, what's up?' Gyaldem is a group of girls, and shan means unfair.
One problem faced by film-makers and scriptwriters is that slang is different in different towns, and words can have different meanings depending on location. However, thanks to mobile phones and social networking sites, regional slang spreads quickly. Even within one area there can be preferences for one word over another. One of the consultants to Sket wanted the word 'busted', meaning 'ugly', to be used, but another local slang word with the same meaning - butters - was used instead.
For an article on this on the BBC website, see here.