Hey Jack, What's In The Sack?

Hey Jack, what's in the sack?
What's in the sack
That you're carrying on your back,
Jack?

It bounces and it moves,
I think that I can hear it talk
it makes you go so slowly
And stumble when you walk.

I know they say that you're deranged
And I think that it's alive
I know that something's very strange;
I think you have someone inside.

Now I know I heard a voice,
It sounded like a cry.
I thought I heard a whimper
But I don't want to pry

Its heavin' and it's movin'
And it's rollin' out the door
It's little Billy Nicholson--
Say what'd you have him in there for?

Hey Jack, what's in the sack?
What's in the sack
That you're carrying on your back,
Jack?