Some Guy tries to blow up Parliament... and the British celebrate this every year! Yep, in 1605, Guy Fawkes tried to blow up Parliament with a bunch of gunpowder because as a Catholic, he felt King James to be a poor ruler. (The Puritans didn't like him so well, either.) In any event, every November 5th, the people of Britain celebrate Guy Fawkes Day. It wasn't really a great day for him, though, because that's the day the King stuck him up in the Tower of London to be tortured until he confessed.
Here in America, of course, we don't celebrate people who advocate the overthrow of our government. Just true patriots of the Revolution. Big difference.
"In an interesting example of semantic progression, Guy Fawkes has become immortalised by one of the most common words in the English language, particularly in American spoken English. The burning on 5 November of an effigy of Fawkes, known as a "guy," led to the use of the word "guy" as a term for "a person of grotesque appearance" and then to a general reference for a man, as in "some guy called for you." In the 20th century, under the influence of American popular culture, "guy" gradually replaced "fellow," "bloke," "chap" and other such words there and the practice is spreading throughout the English-speaking world."