There appear to be a number of versions of this song floating
around. 
Here is the one which appears in the Girl Guides of Canada
Campfire Activities Book:

Once upon a time in a nursery rhyme there were three bears 
One was a Mama Bear and one was a Papa Bear, and one was a Baby
Bear 
They all went a-walkin' in the great woods a-talkin' 
When along came a little girl with long flowing golden hair 
Her name was Goldilocks 
No one was there 
She didn't care 
She walked right in and had herself a ball 

Home came the three bears. (Sing "Dum-da-dum-dum" for suspense) 

Someone's been eating my por-ridge, said the Papa Bear, said the
Papa Bear 
Someone's been eating my por-ridge, said the Mama Bear, said the
Mama Bear 
Hey ba ba ree bear, said the little wee bear, someone has broken
my chair, aah! 
(Throw arms up on "Aah!") 

Just then Goldilocks, she woke up and broke up the party and beat
it out of there 
Bye, bye, bye, said the Papa Bear, said the Papa Bear 
Bye, bye, bye, said the Mama Bear, said the Mama Bear 
Hey ba ba ree bear, said the little wee bear, someone has broken
my chair, aah! 
(Throw arms up on "Aah!") 

So ends the story of the Three Bears