Geary was signing the other day "whistling obscene songs in Memphis" which
implicated that whistling can be a 'whistled language': while obscene does
not just pertain to language, it may specifically pertain to the LYRIC of a
song, rather than its tune (he says he's tone-deaf).
O. T. O. H., McEvoy was quoting P. M. S. Hacker (I think) recalling Frank
Plumpton Ramsey (such was his charming name) and his (Ramsey's) answer to
Witters: what you say is nonsense, and serious nonsense and that. "But I can
say it", Witters protested. Ramsey famously reparteed: "No, you can't say
it, and you can't whistle it either".
In Turkey it's a different matter. A version of whistled Turkish is used to
communicate over long distance in the mountainous terrain of nourtheastern
Turkey. This whistled language (there are others) is used by 30,000 people
today -- and that does NOT include either Witters or his Cambridge friend
Ramsey.
Cheers,
Speranza