The Hamlet Project

Boy? We’re getting a bit familiar with this ghost now, aren’t we?
He’s a king, for one thing and your father and you’re calling him “boy?”
I have a pretty familiar relationship with my dad in the much more casual 21st century, and still I cannot imagine calling him “boy.”
Is it possible this is a close approximation to a “whoo boy!” exclamation?
As in “whoo boy it’s hot outside” or “Whoo boy I’m tired.”
“Whoo boy there’s a ghost’s voice rising up through the floor!”