Question: What Cantonese slang term with a history of racially deprecatory usage was also used as a reference in the title of a 2006 drama directed by Nick Broomfield?

Context paragraphs:
Battle for Haditha: Battle for Haditha is a 2007 drama film directed by British director Nick Broomfield based on the Haditha killings.  Dramatising real events using a documentary style, "Battle for Haditha" is Broomfield's follow up to "Ghosts."  The film was aired on Channel 4 in the UK on 17 March 2008.

Gaoli bangzi: Gaoli bangzi () is a common Chinese slang term, and has a long history of being used as a deprecatory ethnic slur for Koreans.  The term "gaoli" (高麗) refers to the ancient Korean dynasty Goryeo, while "bangzi" (棒子) means club.  It is used synonymously with Er Guizi (二鬼子) and is sometimes shortened to "han bangzi" (韓棒子) or simply "bangzi" (棒子).

Cantonese slang: Cantonese slang is a type of slang used in areas where Cantonese language is spoken.

His Big White Self: His Big White Self is a 2006 documentary film made by Nick Broomfield.  It is a follow-up to his 1991 film "The Leader, His Driver and the Driver's Wife".  It was shown for the first time as part of More4's Nick Broomfield week which started on 27 February 2006.  The documentary follows Broomfield as he returns to South Africa 12 years after the collapse of the apartheid regime.  His previous film focused largely on JP Meyer, a driver for Eugène Terre'Blanche (the leader of the far-right Afrikaner Weerstandsbeweging), and JP's wife, Anita.

Gweilo: Gweilo or gwailou (, pronounced ] ) is a common Cantonese slang term for Westerners.  In its unmodified form, it applies only to European ethnicities and has a history of racially deprecatory use.  Cantonese speakers frequently use "gwailou" to refer to Westerners in general use, in a non-derogatory context, although whether this type of usage is offensive is disputed by both Cantonese and Westerners alike.

Zips: Zips (also Siggies or Geeps) is a slang term often used as a derogatory slur by Italian American and Sicilian American mobsters in reference to newer immigrant Sicilian and Italian mafiosi.  The name is said to have originated from mobsters' inability to understand the faster-speaking Sicilian dialects, which appeared to "zip" by.  Other theories include pejorative uses such as Sicilians' preference for silent, homemade zip guns.  According to still another theory, the term is a contraction of the Sicilian slang term for "hicks" or "primitives."  The older Sicilian mafiosi of pre-Prohibition known as "Mustache Petes" (who eventually were deposed by American-born mobsters during the Castellammarese War) were also referred to as zips.

The Leader, His Driver and the Driver's Wife: The Leader, His Driver and the Driver's Wife is a 1991 British feature-length documentary film set during the final days of the apartheid regime in South Africa, particularly centring on Eugène Terre'Blanche, founder and leader of the far-right Afrikaner Weerstandsbeweging.  The film was directed by Nick Broomfield and released in 1991.  It received an average of 2.3 million viewers during its screening on Channel 4.  A year later it was the subject of legal action brought by the journalist, Jani Allan, in what has been described as "the libel case of the summer".  In 2006, Broomfield released a follow-up, "His Big White Self".

Ghosts (2006 film): Ghosts is a 2006 drama film directed by Nick Broomfield, based on the 2004 Morecambe Bay cockling disaster.  The title is a reference to the Cantonese slang term "Gweilo" (鬼佬), meaning "ghost man", used for white people.

Diamond Skulls: Diamond Skulls (also known as Dark Obsession) is a British 1989 thriller directed by Nick Broomfield who also co-wrote with Tim Rose-Price.  An established documentary filmmaker, this is Broomfield's first work of fiction.It is produced by Tim Bevan and Jane Fraser and stars Amanda Donohoe, Gabriel Byrne and Struan Rodger and has a music score by Hans Zimmer. It includes the last film performance of Ian Carmichael.

Beard (companion): Beard is a slang term describing a person who is used, knowingly or unknowingly, as a date, romantic partner (boyfriend or girlfriend), or spouse either to conceal infidelity or to conceal one's sexual orientation.  The American slang term originally referred to anyone who acted on behalf of another, in any transaction, to conceal a person's true identity.  The term can be used in heterosexual and homosexual contexts, but is especially used within LGBT culture.  References to beards are seen in mainstream television and films, and other entertainment.

Supporting paragraphs: Ghosts (2006 film) Gweilo
Answer: Gweilo