I like the one that went:
"From the tiny ant (from the tiny ant) to the elephant
From the snake to the Kangaroo"

and the one about the good Samaraitan that went
"Cross over the road my Friend
ask the Lord his strengh to lend
Everytime you need a friend
Cross over the road"

but when we were being naughty we'd change to
"Cross over the road my Friend
There's a Lorry round the bend
If you want your life to End
Cross over the road".