I'd always thought it was an attempt at spelling a snore. How else would you spell that?
Noises often have unexpected written representations, and they are surprisingly different in different languages. For example French water goes "plouf" not "splash".
New Forester - the point about other language's versions of sounds is really interesting to me. Did you know french dogs go, "Oua, oua" and french sheep go "B�"? And the ducks go, "coin-coin"!
In Russian, the dogs go 'gaf gaf', and the sheep go 'be-e-e' and the frogs go 'kvaaa', and the ducks..the ducks omit a rather horrifying 'krya krya' noise :) How strange that the same noise would be so different in different countries. I wonder how ducks go in China?
I remember being told by my French teacher at school (a few months B.I.) that French football commentators use the English word and shout "Cornère!" whenever there is a corner, otherwise it would sound as if they were quacking. (The French word for "corner" also being "coin")