Wog is a word with several meanings, one commonly derogatory, the others not.
As a racial epithet in British English
British racial term originating in the colonial period of the British Empire. It was generally used as a label for the natives of India, North Africa and the Middle East. By the 1950s it had become a pejorative term used in order to offend.
The origins of the term are unclear. Most dictionaries say "wog" either possibly or likely derives from the generic term golliwog after the Golliwogg, a "grotesque" blackface minstrel doll-character from a children's book published in 1895. Various facetious explanations include the claim that it originated from acronyms for "Westernized/Worthy/Wily Oriental Gentleman" or variants thereof, or for "Workers of Government" or "Wards of Government", used to refer to early immigrants into the United Kingdom. Such attempts to explain the word's origin are apocryphal at best.
The use of the word is discouraged in Britain, and most dictionaries refer to the word with the caution that it is slang, derogatory, and offensive. James Robertson & Sons, a British manufacturer of jams and preserves, discontinued use of the Golliwog as its trademark in the early 1990s for similar reasons. It is generally considered unwise to use it in modern Britain without expecting an extreme reaction.
The saying "The wogs begin at Calais" was originated by George Wigg, Labour MP for Dudley, in 1945. In a parliamentary debate concerning the Burmese, Wigg shouted at the Tory benches, "The Honourable Gentleman and his friends think they are all 'wogs'. Indeed, the Right Honourable Member for Woodford [i.e. Winston Churchill] thinks that the 'wogs' begin at Calais." Wigg's coinage, sometimes paraphrased as "Wogs start at the Channel" or "Wogs start at Dover", is commonly used to characterise a stodgy Europhobic viewpoint, and more generally the view that Britain (more commonly England) is inherently separate from (and superior to) the Continent. In this case, "wog" describes any foreign, un-English person.
As a racial reference in Australian English
Wog is also a slang term in Australian English, denoting non-Anglo-Celtic Australians, usually people of Southern European Mediterranean ancestries. These days it is still applied to Greeks and Italians but is also used with Arabs or Turks. Historically, the term included Slavic peoples
This meaning came into popular use in the 1950s when Australia accepted large numbers of immigrants from Southern Europe. Although originally used pejoratively, the term is increasingly used more affectionately, especially by the individuals the term is used to describe. Wog is a word with definite and widespread currency in contemporary Australian English, and for the most part it is rarely considered to be the sort of slur or insult that it remains in other parts of the Anglosphere.
The process by which it has become embraced by the communities it describes is similar to the reclaiming of gay and poof in the homosexual community, a process designed to take the sting out of the pejorative. The process was accelerated in the early 1990s with the popularity of the stage show Wogs Out of Work starring Greek-Australians including Nick Giannopoulos, George Kapiniaris and Mary Coustas. The production was followed on television with Acropolis Now, and in film with The Wog Boy.
Nevertheless, this process of reclaiming the word is only partial and is mainly restricted to ethnic groups broadly accepted by the dominant white Anglo-Celtic ethnic group. The term remains quite offensive to a lot of people in Australia, particularly people of non-anglo origin who grew up in Australia during the 1950s, 1960s and 1970s. In those times the word was usually used as a racist slur or insult. Its use was often preceded by a word such as "dirty", "greasy" or an expletive such as, "fucking".
In Australia, the word is still used as a racial slur. For example, in December 2005, the term was used frequently in its pejorative sense before and during the Sydney race riots.
As a synonym for "illness" in Australian English
Wog has also been used in Australia as a slang term for illness such as colds, the flu or malaria. This usage has been in existence since at least the early 1940s. It is recorded in the 1941 Popular Dictionary of Australian Slang by S. J. Baker as meaning a germ or parasite.
The derogatory nature of the term when used as a racial taunt largely succeeded in overtaking and driving out use of the term wog to describe illness or undesirable insects. In common parlance, the word no longer has much currency in these contexts, and many young Australians would be unfamiliar with this usage. Nevertheless, older usages may occasionally be referred to ironically or humourously. For example, The Australian National Dictionary cites a joke in a publication called Nichigo Press from 1983:
- Have you been in bed with a wog? Oh no, I'm married! 
Wog is a shortened version of the word polliwog (frequently modified with the word slimy), used for sailors during the Line-crossing ceremony on the first time they cross the equator. Polliwog or pollywog is an increasingly obsolete synonym for tadpole which has been traced back to Middle English.
This use of polliwog goes back to at least the 19th century and thus may be the oldest source of wog. Dictionaries are unaware of it, possibly because Eric Partridge missed it in his Dictionary of Slang and Unconventional English (1937).
Maritime wog is a possible alternative ancestor of the racial wog, particularly since Partridge does record a usage for presumably annoying Bengali bureaucrats:
"A lower-class babu shipping-clerk: nautical: late C.19-20" - Concise Dictionary of Slang, Eric Partridge, 1989
As a term in Scientology
Scientologists use "wog" disparagingly for non-scientologists. Scientology's founder L. Ron Hubbard employed the term frequently in his lectures and writings, and his followers in the Church of Scientology continue to do so. From a 2000 staff recruitment leaflet:
"Why spend your time and ability working a 9 to 5 job in the wog world, when you can be 100% on-purpose, working full-time to help change conditions and Clear the Planet?"
As Hubbard had been an officer in the U.S. Navy during World War II, his usage may have derived from the maritime rather than the racial meaning.