Shall I assume everyone has heard the Kentucky version done by Jean Ritchie during the 1940s-50s? Called "The Boo Song" by my youngest son (now 34), it was his favorite lullaby!!!

There was an old woman all skin and bone.
Ooo-oo-oo-oo
She lived down by the old churchhouse.
Ooo-oo-oo-oo

One night she thought she'd take a walk.
(Ooo------)
She walked down by the old churchyard.
(Ooo----)

She heard the bones a rattlin' 'round.
(Ooo----)
She thought she'd sweep the old churchhouse.
(Ooo----)

She went to the closet to get the broom.
(Ooo----)
She opened the door and
BBOOOOOOOO!!!!!!

He could be absolutely sack-of-potatoes slumped asleep and giggle in his sleep at the end. I would start with the other popular ones (in our family)-- Hush/word/mockingbird, Go Tell Aunt Rhody, my grandmother's peculiar version of Whole Heap of Little Ponies, etc.-- and when he couldn't keep his eyelids open any more he would ASK for "The Boo Song, mommy."