"Please to remember..."
...that "guy" as a generic term for a male is a recent development. This is one of my historical fiction pet peeves (second only to the use of "okay" in stories set before the mid nineteenth century).
As all you Brits will knows, Guy Fawkes was a Catholic in the 16th-17th centuries who was known for his involvement in the Gunpowder Plot to assassinate the protestant King James. (Whether or not he was framed is a question for another day...) Since the early seventeenth century, his arrest and execution have been *tastefully* celebrated on the fifth of November (Guy Fawkes' Day) with fireworks and a burning of his scarecrow-ish effigy.
Because of this, the term "guy," in the nineteenth century, came to mean a poorly-dressed or ridiculous-looking man. It developed to mean a foolish man; I will always remember the noble Tom begging Fanny's forgiveness in An Old-Fashioned Girl by declaring something like, "I'm sorry for being such a guy."
Using the term casually, in a non-derogatory way, to describe a young man, didn't crop up until the mid twentieth century.
So, please...remember. Or I will be forced to call you a guy. In a nineteenth century tone of voice.