In itself, there’s nothing uncommon or weird about this expression, though it will not be so familiar to people outside Britain and the Commonwealth. It refers to an annual British celebration on 5 November which is also often called bonfire night or firework night. This year’s celebration is special, however, since 5 November 2005 is the 400th anniversary of the attempt by Guy Fawkes and his fellow conspirators — as a Catholic protest against the policies of the Protestant king, James I — to blow up the Houses of Parliament and with it the king and peers who were assembled for the state opening of Parliament. For various reasons, this rather inept conspiracy became famous, in part because of one-time strong anti-Catholic sentiment (the famous celebrations in Lewes in East Sussex each year still burn the Pope in effigy). The link of bonfires with the plot began the day it was discovered, as Londoners were encouraged to light fires in the street to celebrate the king’s deliverance, provided that “this testemonye of joy be carefull done without any danger or disorder”. Fireworks became associated with it in the 1650s. Guy Fawkes wasn’t the ringleader, but he became most deeply linked with the plot in the public mind because he was discovered on the scene, having been deputed to light the fuse. The plot is also commemorated in the rhyme: Remember, remember the fifth of November: Gunpowder, treason, and plot. We know no reason Why gunpowder treason Should ever be forgot! Most famously, it also bequeathed us guy. At first this meant the effigy of Guy Fawkes traditionally burnt on the bonfire (children once constructed guys and begged money with them for fireworks with the cry “a penny for the guy!”). But it’s also where guy in the sense of a person comes from — it was originally applied to a man of grotesque appearance, like a bonfire effigy, but when it was taken to the US in the late nineteenth century it turned into a neutral term for a man, more recently (in the plural) persons of either sex. It was also used for a person who acted as a dupe in a confidence game and led to the verb to guy, to ridicule or hoax.