Irish & Yiddish

I am currently reading Just Say Nu, a very funny book by Michael Wex where he teaches non-Yiddish speakers that any word in Yiddish can be made into a very useful insult instantaneously. Yiddish is a language that relies heavily on irony and you can almost pick any word and turn it into a sharp object with the right context and the right amount of impatience and contempt.
I'm having a ball because I recognize many phrases my Mom and her side of the family used to say (for instance: gay kakn afn yam, "go shit on the sea", and other lovely turns of phrase). My only kvetch about the book is that Mr. Wex has chosen to transcribe a dialect of Yiddish that is not how my family spoke it, and therefore it sounds horrible to me. But I still laugh at some of the expressions. And I love that we even have a word for email! Blitz-post. I think it is possible that the internet, to judge from some sites I've been consulting, may help avert the death of Yiddish, a language that as any good kvetch, has been dying forever, but is still hanging in there.
English has adopted some very useful Yiddish words that are now part of the language, at least here in the States. Putz, Schmuck, Mensch, Shlep, etc.
I'm delighted to read that many wonderful words we have in English actually come from the Gaelic. Like dork, or jerk or "cry uncle". It is these foreign words that help give English its wonderful snap.