I’m second generation American by way of Sicily. I started to pick up some of the lingo when I was a very young boy from my aged Grandfather.
My Grandmother came down on me like a hawk.
‘We’re in America now! Speak English!’
This was in 1954 when I was nine years old.
End of discussion.
My Grandfathers parents came from Norway, but he never learned Norwegian. English only, except for saying “ja” instead of yes. My mom says it, too. Even I do occasionally.
It’s just the way it was done-you assimilated.