"Whack" is an old sailor's term for daily ration, which included all food and water, (and for a while, rum.)

If "daddy-o" could refer to the singer (as in "Come to Papa,) then "Whack for my daddy-o" might roughly translate to "I have all that I need, because there's whiskey in the jar."

As for the "Musha ringum ...," that's what brought me here.