`Be a good chap, and tell us where the word chap comes from," writes somebody who signs his or her letter Fingall Harrier.
Chap, young man, is an abbreviation of chapman, a purchaser, buyer, customer, and is rarely found in literature before the end of the 16th century. Indeed I can't find any reference to it prior to 1577 when Nicholas Breton, in Toyes Idle Head, has "Those crusty chaps I cannot love, The Divell do them shame."
Even the dramatists, those most likely to use slang, cant or abbreviations, did not use the word before 1700; the first literary use of it after Breton's is from a medical dissertation by a man called Davies, written in 1716. He mentions some "country chaps" and by that he meant young fellows. Dr Johnson hated the word so much he refused to include it in his dictionary; Bailey's eccentric dictionary of 1731 has chap, but gives the old definition of a chapman, as customer. From then on chap, for some unknown reason, became simply a young lad.
A young woman of my acquaintance told me the other day she was cock-a-hoop; she had just got engaged.
Blount's Glossographie of 1670 has this nice bit of hokum: "Cock-on-hoop or ancestors called the Cock which we call the Spigget, or perhaps they used such as water-pipes; the Cock being taken out and laid on the Hoop of the vessel, they used to drink up the ale as it ran out without intermission, and then they were cock-on-hoop, i.e. at the height of mirth and jollity."
The trouble with that is that there is no evidence that cock ever meant a spigot; and if it ever did, why would they lay it on the hoop of a cask? Still, Thomas More had the notion of drink flowing freely in his Comfort Against Tribulation in 1529: "They set them downe and dryncke well for our saviours sake, sette cocke a hoope and fill in all the cuppes at ones, and then let Christes passion paye for all the scotte."
To further confuse matters, Cock-on-the-hoop was seen on tavern signs as far back as the reign of Edward 111. And few believe that the phrase comes from the French, coc a huppe, a crested cock, hence a roisterer.
Nowadays, by extension, the phrase means "on top of the world". This meaning was known to Shakespeare. In Romeo and Juliet he has "you'll set cock-a-hoop! You'll be the man."