Jack and Jill went up the hill
to fetch a pail of water
stupid Jill forgot her pill
and now they have a daughter!
My mom caught me swinging on the closeline singing this one day, and made me hold a bar of Fels Naphtha in my mouth for ten minutes -- and I didn't even know what "forgot her pill" meant...

Also...
See, see my playmate
Come out and play with me
And bring your dollies three
Climb up my cherry tree
Slide down my rainbow
Into my cellar door
And we'll be jolly friends
Forevermore
One, two, three, four....
See, see my enemy
Come out and fight with me
My dolly has the flu
I'll make you cry, boo-hoo
Slide down my razor blade
Into my dungeon door
And we'll be enemies
Forevermore

and, don't forget the immortal Miss Mary Mack, and the Lady with the Alligator Purse -- do those count as songs?