I am a New Yorker at large.
My students often say, en masse, “say kwafee”. I tell them to “get back to work”.
Irish indeed.
I never noticed the linguistics re the Irish. I believe you have a good point. I know the German influence is there. They cannot say “th”. Used to drive them crazy (Germans) when I would get them prepared for a visit from a cousin “Marybeth, Kathleen”- Of curse, Caitlin in the Irish.
German, Yiddish, Dutch, Irish, I guess Italian, and the need for speed in communicating all contribute.
Modern New York has a great deal of black influence in the way people speak. And, possibly, a Hispanic infusion. And, of course, mid-20th century was dominated by the Jews and the Yiddish contribution. That, gladly, still hangs on.