In another thread, Jackie referred to Ullrich as "bub." What could she mean by that?

Might it be a shortened familiar form of Beelzebub?

A derivative of the Yiddish bube -- meaning sweetie, darling.

A shortening of the Southern American bubba -- meaning a good old boy.

A use of the 19th Century British bub for a male pal.

... or something else?