The Phrase Finder has a good entry on what is now perceived as the Cockney exclamation “Wotcher,” which is actually the much older “What cheer?” in disguise; the latter goes back to at least the fifteenth century (York Mysteries, circa 1440: “Say Marie doghtir [daughter], what chere with ye?”). There are all sorts of goodies there, including this list of greetings my parents probably chuckled over in their youth:
In the mid-20th century, there was something of a fashion in the US for jocular greetings, in the same vein as the nonsense ‘enthusiasm’ phrases like the bee’s knees, the cat’s pyjamas etc.
Hello Joe, what d’ya know?
What’s buzzin’ cousin?
What’s knittin’, kitten?
What’s steamin’ demon?
What’s tickin’, chicken?
What’s your story, morning glory?
What’s your tale, nightingale?
What’s on the agenda, Brenda?
And at the end it explains why it’s now thought of as Cockney (it all has to do with Albert Chevalier, “The Singing Costermonger,” and his signature tune “Knocked ‘em in the Old Kent Road”). This comes courtesy of a MetaFilter post (by the wonderful Jessamyn West) on a San Francisco institution forgotten for a century or more, Woodward’s Gardens (1866-1891), which developed from a temperance hotel called the What Cheer House.