The webiste for The Cathedrals attributes this to George Younce, but in at least one performance he says some one, (perhaps Glenn Payne?) brought it to him.

The Laughing Song
Author: George Younce.
Copyright: Homeward Bound Music (BMI). Used by Permission.
Album: It's Music Time (1970)
Album: Everything's Alright (1971)

Oh, my name is "Ticklish Reuben" from way down in old Vermont
I've been tickled by almost everything
I've been tickled by a feather, I've been tickled by a wasp
I've been tickled by a yellow bumblebee

Oh, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha
Oh, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha
Oh, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha
Oh, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha

Oh, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha
Oh, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha
Oh, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha
Oh, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha

Oh, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha
Oh, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha
Oh, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha
Oh, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha, ha

That's all, folks!

George Younce, The Laughing Song