Jack and Jill went up the hill
to fetch a pail of water,
Jill forgot to take her pill
and now she's got a daughter.

Dave the Gnome, my Nan used to sing me the Nebuchudnezzar (sp?) one, I remember it as:
Nebuchudnezzar the king of the Jews
Bought himself a pair of shoes
When the shoes began to wear
Nebuchudnezzar began to swear, swear, swear, swear...