IN ANSWER TO YOUR QUESTION
I haven't used Pig Latin in a while, though.
And I never could speak Valley.
My mother forced me to read Beowulf and some other stuff in Old-English, so at this point I can recognize it when I see it, but I seldom want to think about it. In fact, I'd much rather not.
Thanks to second-hand bookstores, the San Francisco social environment, and the internet, however, much more has crossed my horizon.
THE ALL-TONGUE BUFFET
My ability in Indonesian and Hindi/Urdu is somewhat less than passable, plus I've almost quite forgotten Hokkien, Tokpisin, Limburgisch, Danish, Latin, Tagalog, Tausug, Igorot, and an Indonesian regional language. I went through a few Sanskrit lesson books and dictionaries, found the grammar fascinating, and forgot most of it since then. Failed French four years in a row when I was in high-school ("bonjour, parlez vous une langue civilisée?"), and now only read it badly.
Both Old Franconian (Germanic) and Old French (Gallo-Romance) are fascinating, but remain dead to my mental ear. Which is not surprising, though I used to know a few people for whom both tongues came alive.
Occitan remains, sometimes, an interesting perversion.
Hebrew only in transcription, and only Ashkenazis.
I was once semi-able to hold simple conversations in Punjabi, Tajik, Persian, Arabic, Sranantongo, and Papiamentu, but that didn't last very long. Still read medieaval Dutch, but that shades through various stages into early modern Dutch, Dutch dialects, and literary Dutch, so it ain't difficult at all. Once I discovered them on Wikipedia I also looked at Alemanisch, Boarisch (Bavarian), Deitsch, Frysk, West-Vlams, and a whole ton of brand-new Malayo-Polynesian tongues, and that was great fun.
Dabbled superficially in Venetian, Sicilian, and Sassarese.
They would be too difficult to pursue.
I used to try to get to sleep at night by reading dictionaries of languages spoken the Muslim world and trying to spot the Arabic borrowed words.
In all the Turkic languages that can be enjoyably challenging.
It kept me awake instead.
Sometimes I feel like Barbara Billingsley in the classic movie 'Airplane' (1980), who has one immortal line that everybody knows.
"Oh stewardess, I speak Yeshivish!"
Surely you remember that?
THERE IS A LINK THAT TIES THEM TOGETHER
Basically, I am the arch-type of a total dilettante in Medieaval studies, Germanic studies, Jewish-Talmud-Torah studies, Islamic world studies, Asian studies, Subcontinental studies, and Dutch-Colonial studies.
All of these subjects shade into each other.
A rabbi I know studied Japanese, Irish Gaelic, and linguistics, in addition to Talmud-Torah. He also drives a forklift, and wields a mean sewer snake.
He's what you would call a well-rounded Yekki.
I am not sure how his skills meld.
Maybe they don't.
I dream in gibberish.
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