The name Sir is a boy's name . Sir and is often added to lists like Middle Names for Boys.
From the experts:
We've got Saint, we've got King, we've got Prince Duke Bishop Deacon and Messiah. So why not Sir? The name of Beyonce and Jay-Z's newborn son, Sir is an honorific and a word name that fits right in with current trends. And it does guarantee your son will be addressed with respect, at least nominally.