I look at 'em as if they have three heads and laugh. Depending on the subject matter (Mary, confession, purgatory, saints, statues, Bible) I look 'em in the eye and say: “I don’t know where in the world people get all these crazy ideas about the Catholic Church.” That’s about all most of 'em can take, since they’re used to Catholics cringing, being lost for words, and crawling away.
Then I’ll ask, in my brightest, friendliest tone, “Do you want to know where in Scripture we get that?” I don’t wait for an answer but launch right into my 45-second apologetic, followed by, “See? It’s all right there in the Bible!”
They’re usually so shocked that a Catholic has anything resembling a non-defensive, scripturally based position that THEY are the ones lost for words.
Unfortunately, when they encounter a Catholic with a fast mouth and a quick trigger-finger on Scripture, they don’t come back at you again. Shucks!