There is a branch of the Babauta clan who live in Saipan who are called the Familian Sa'i.
The family themselves tell me that the origin of this family nickname comes from an ancestor who had six toes.
Well, in Chamorro, "six" is sais. The man, to make up an example, would have been called Josen Sais, as in "Six Toed Joe."
In time, sais became sa'i, either because someone just wanted to give it a twist, or perhaps because sa'i hid the fact that an ancestor had six (sais) toes.
Former CNMI Governor Juan N. Babauta
Member of the Sa'i Clan