Say, Say my playmate
Come out and play with me
And bring your dollies three
Climb up my apple tree

Slide down my rain barrel
Into my cellar door
And we'll be jolly friends
Forever more - more - more !

Say, say oh playmate,
I cannot play with you.
My dolly has the flu,
Boohoo, hoohoo, hoo, hoo.

Ain't got no rain barrel,
Ain't got no cellar door.
But we'll be jolly friends,
Forever more - more - more - more - more!!

Version 2:

Say say oh playmate
Come out and play with me
And bring your family three
Climb up your apple tree

Slide down my rain spout
Into my cellar door
And we'll be jolly friends
Forever more more more

Version 3:

(ed: Erica has sent in some really good stuff... here's another offering:)

In the 70's my first-grade friend and I used to follow up "say say oh playmate" with this version. I don't think that we made it up ourselves...

Say say oh enemy
Come out and fight with me
And bring your pistols three
Climb up my poison tree

Slide down my razor blade
Into my cellar door
And we'll be enemies
Forevermore - more - more,more,more,more...