Don't cry-ee! Don't sigh-ee!
There's a silver lining in the sky-ee
Bon soir old thing! Cheerio, chin-chin!
Nahpoo! Toodleoo! Goodbye-ee!
From the popular WW1 song Good-bye-ee, by Weston and Lee. Look out for it in Oh What A Lovely War.
What does chin-chin mean though? I always vaguely imagined it was an English-Languge expression for "cheers" and to do with two people holding glasses to their chins to toast one another.
But no! It seems to have come into English and many other languages from Italian cincin (pronounced the same). I found several explanations, such as it being derived for the name of the famous vermouth, or the sharp sound made when two drinking glasses gently collide.
But these informal etymologies, though appealing, are almost certainly wrong. The word appears to be from a Europeanised version of Chinese quing-quing,請請, which means something like "please, welcome". Why it came first into Italian I don't know.
Napoo is for another day.