Q. I saw in the Siddur a reference to a rabbi called Ben Bag Bag and another called Ben Hey Hey. Can you explain how anyone would have such a crazy name?
A. The passage you are quoting is from the end of chapter 5 of the Mishnaic tractate Pirkei Avot (The Ethics of the Fathers). Both rabbis, 1st century sages from the Land of Israel, are summing up the rewards that come from studying Torah. One gets the impression that they came to it from outside and found that their effort paid off.
Many scholars think they are converts (one view has it that they are one and the same person). Bag is composed of two Hebrew letters, bet and gimel, denoting 2 and 3 – added up they make 5, the numerical value of the letter hey, which was added to the names of Abraham and Sarah. Hey is one of the letters from the Name of God, and so Ben (son of) Bag Bag may have been given his name when he adopted Judaism. Likewise with Ben Hey Hey.
Ben Bag Bag plays a part in the halachic tradition, e.g. in the Sifra on Lev. 19:11-14, where he says, “Do not steal back from a thief that which he has stolen from you, lest you appear to be a thief.”