Taig is a derogatory term for an Irish Catholic. It is mainly used by sectarian loyalists in Northern Ireland and Scotland. It has been used in sectarian slogans such as "Kill All Taigs" (KAT), "All Taigs Are Targets". (ATAT)
The term is a synecdoche derived from the Irish male given name Tadhg, which is commonly translated as Tim. The name Tadhg was once so common as an Irish name that the name itself came synonymous with the typical Irishman in a the same way that Paddy or Mick might be today.
Hence, Irish phrases such as Tadhg an mhargaidh (lit: Tadhg of the market) or Tadhg na sráide (lit: Tadhg of the street) are similar to the English-language expression "average Joe" or "the man on the street" among other similar expression. However, when used in English the name carries derogatory connotations.
Unlike Paddy, another derogatory term for an Irish person, Taig usually implies that the person has Irish nationalist sympathies. Also, whereas Paddy is often used in a jocular context or incorporated into mournful pro-Irish sentiment (e.g. the songs Poor Paddy On The Railway and Paddy's Lament), the term Taig remains a slur in almost every context. It has also been used to describe Irish Catholics perceived as a threat to law and order. Sometimes the term is widened to include all Roman Catholics.
Teague has been reclaimed by some Irish nationalists as an ironic self-identifier in the same way that other terms of disparagement have been adopted by certain people they describe. In contemporary sources, the difference in spelling between taig and teague often indicates a difference in connotation akin to the difference between nigger and nigga.
In the late 1680s, the term appears in the satirical Williamite ballad Lilliburlero which includes the line "Ho brother Taig hast thou heard the decree?" In 1698, John Dunton wrote a mocking account of Ireland titled Teague Land - or A Ramble with the Wild Irish. Thereafter the derogatory use of the term was frequent.
However, there is also evidence from this era of the word being used as a self-identifier by rebellious Irish Catholics. An Irish language Jacobite poem written in the 1690s includes the following lines:
"You Popish rogue" is not spoken
but "Cromwellian dog" is our watchword,
"Who goes there" does not provoke fear,
"I am Tadhg" is the answer given
Although the term has rarely been used in North America, a notable example of such use was when John Adams successfully defended the British Army soldiers responsible for the 1770 Boston Massacre by pleading to the jury that the soldiers were acting in self-defence against: