Chav

When she inhabited the body of Rose Tyler, Cassandra O'Brien, upon examining her new body in the mirror, exclaimed, to her dismay, that she was a chav. Later, when returning to Rose's body after briefly inhabiting the Tenth Doctor, she frustratedly said that she was "chavtastic" again. (TV: New Earth)

Tamsin Drew also called Lucie Miller a "chav extraordinaire". (AUDIO: Lucie Miller)

Martyn took offence when Gwen Cooper called him a chav. She told him to f*ck off. (AUDIO: Smashed)

Behind the scenes
Though not specifically defined in the body of Doctor Who fiction, this epithet was perhaps in such broad use in British culture during Rose Tyler's tenure that an in-narrative definition would have been insulting to the BBC One audience. It essentially means a working class, urban youth of lower educational achievement, with a somewhat banal dress-sense and lifestyle.