So I went to an "elite" high school in Turkey and one of my friends had the last name Sevi, which is the Ottoman equivalent of Zevi. Jewish guy but didn't know at the time. My high school had many Jews but he was a lot less Jewish than they were so almost didn't notice. Many years later I have come to realize that all the Jewish students in my year were actually somewhat connected via the synagogue and all their families knew each other.

Either way, in Turkish, if your buddy were to make a joke that could be construed as sexually objectifying children, it is common place to react with "wtf dude, are you a Sabbatean?". Nobody really truly knows why, it is just a phrase.

In Turkey Sabbateans are known as Jews that are putting up a facade of being Muslim or Christian. Even their children are rumored to not know about coming from a Sabbatean family until their marriage ceremony. It is revealed only then.

Even Ataturk, founder of modern Turkey is rumored to be coming from a Sabbatean family. A good detail pointing to that being the elementary school he went to serving exclusively to the children of Sabbatean families among other things.