Nonsense song by Milton Drake, Al Hoffman, and Jerry Livingston, 1943. It caught the imagination of the nation in wartime, in need of a break in the somber mood.

The story is that the incomprehensible words were actually imitations of a small person talking very rapidly and seeming to make sense with words that seem to make none. One plausible possibility:

Mares eat oats and does eat oats,

And little lambs eat ivy.

A kid'll eat ivy,

too, Wouldn't you?