I've just posted something in the "fairy tales suitable for children" thread. And it reminded me of this song (note: there are many versions of this book - another version is called "The Cruel Mother", another, "Old Mother Lee").
There was an old woman who lived in the woods
Weela weela wallia
There was an old woman who lived in the woods
Down by the river Sallia

She had a baby six months old
Weela weela wallia
She had a baby six months old
Down by the river Sallia

She had a penknife three foot long
Weela weela wallia
She had a penknife three foot long
Down by the river Sallia

She stuck the penknife in the baby's head
weela weela walia
She stuck the penknife in the baby's head
Down by the river Sallia

Three big knocks came a-knocking at the door
Weela weela wallia
Two policemaen and a man
Down by the river Sallia

"Are you the woman what killed the child?"
Weela weela wallia
"Are you the woman what killed the child?"
Down by the river Sallia

"I am the woman what killed the child"
Weela weela wallia
"I am the woman what killed the child"
Down by the river Sallia

The rope got chucked and she got hung
Weela weela wallia
The rope got chucked and she got hung
Down by the river Sallia

The moral of this story is
Weela weela wallia
Don't stick knives in babies' heads
Down by the river Sallia
This is a childrens song in a kids song book.

So, do you think this is suitable for a kiddy sing-song? Explain your choice.