When they're looking for Eustace in VDT after he goes missing on Dragon Island, they're describe as shouting, "Eustace! Eustace! Coo-ee!"
I'd never really heard that last part before.
Something online I saw seemed about as confused!
"What is coo-ee?" asked Jack. "No idea, but they said that in the book, they shouted, "Eustace! Eustace! Coo-ee!" And so I decided I wanted to shout coo-ee.".
Is it a real expression?
Here's an explanation from wikipedia. It's an expression I am used to, but I didn't know it origin until I looked here.
http://en.wikipedia.org/wiki/Cooee
There, shining in the sunrise, larger than they had seen him before, shaking his mane (for it had apparently grown again) stood Aslan himself.
"...when a willing victim who had committed no treachery was killed in a traitor's stead, the Table would crack and Death itself would start working backwards."
That is a really interesting article there coracle. Its a fairly common expression in the UK (perhaps more so amongst older generations) but i didn't realise it had any specific meaning other than being a generic call-out like "yoo-hoo!"