This happens to me often (when I travel outside of Israel), and I love it. It shows me that assimilated Jews still have pride in their heritage.
One time, I was in the middle of the United States, and the clerk at the store started counting out my change - in Hebrew.
Other times, people (often older Ashkenazi men) will intentionally toss in a Yiddish word or phrase into our conversation.
My wife and I have come to call it "dropping Hebrew" or "dropping Yiddish".
Used in a sentence, "I was in podunk, Kansas, and the cashier dropped Hebrew on me!"
I was actually unfamiliar with the term "bageling" until very recently.
I was telling a religious friend in the US about a recent occurrence of someone "dropping Yiddish", and he responded, "Oh, you mean he bageled you?"