THE Trojan horse is today a figurative expression used for anything intended to secretly bring about the downfall or defeat of an enemy. With the widening area of the cyber world, it has reached the parlance of computers as well, where a Trojan horse is a programme designed to breach the security of a computer system while ostensibly performing an innocuous function.

The origin of Trojan horse goes back to the legendary 10-year siege of Troy by a coalition of Greeks. They were attempting to recover Helen, wife of Menelaus, who had been abducted by the Trojan prince, Paris. The war ended with the capture of the city through a trick: the Greeks ostensibly ended the siege but left behind a group of men concealed in a hollow horse so large that the city walls had to be breached for it to be drawn inside. The rest is history and the language adopted a new expression.

A running dog is a servile follower or a slavish person; it is a translation of the Chinese zougou, made up of the words zou (running) and gou (dog). This expression came into being as an allusion to a dog running to follow his or her master’s commands. It belongs to the register of the Chinese communists who used it in order to refer to someone subservient to counter-revolutionary interest. Running dog is used today to refer to any unimaginative or hackneyed way of behaving: "We’re playing lickspittle running dog to the most tired ideas, and they weren’t even ours in the first place," wrote Zoe Williams (The Guardian, August 13, 2002).

Kilkenny cats are people who fight relentlessly till their end. It comes from a pair of proverbial cats in Kilkenny, Ireland, who fought till only their tails were left. According to a story, some people in the town of Kilkenny in Ireland enjoyed tying the tails of two cats and watching them fight till the bitter end. This story originates from the record of a contest between Kilkenny and Irishtown, two municipalities that fought without pause about their boundaries.