This new pronoun, which many languages have but no other dialects of English, arose as “you” crashed into an “all” that was added to remove any ambiguity about whether “you” was plural.

Incidentally, “y’all” is not ungrammatical; it’s an example of how languages evolve.

If it feels wrong to you, that’s because it violates one of your internalized linguistic social norms.

Joseph Henrich, Secret Of Our Success

Dear Sirs,
Congratulations (gratulations, felicitations, blessings, compliments, good wishes, best wishes) on your excellent (bueno, bon, bonzer, bonny, fine, nice, goodly, splendid, capital, braw, estimably, virtuous) blog (diary, journal, manifesto, scrapbook, gazette, periodical, serial, ephemeris, pulp, slick, bulletin, psychodrama, playbook, daybook, masturbatorium)!

It certainly is funny (humorous, amusing, witty, droll, whimsical, risible, rich, priceless, farcical)!

National Lampoon

Delphic Maxim: Know thyself.

P Willy: Know y’all selves.