In reply to:

Deck us all with Boston Charlie

I don't remember that wording, but you could well be correct, and probably are. How long has it been (30 years?) since Albert and Pogo used to dance around singing that?

So far, no takers on Adeste Fideles. Those are, of course, the Latin words to "O Come All Ye Faithful", which everyone I know assumes to be a medieval hymn, since it was originally written in Latin. Actually, it was written sometime between 1730 and 1750 by a music stationer (whose name I forgot) at the English college at Douai, France. The Tractarians first introduced it to England in the 1830's, but it never caught on in Protestant churches until the 1880's because of its Catholic origins.