Title character in a piece of doggerel, often sung by firelight and accompanied by ritualistic actions.

Little Rabbit Foo Foo, hopping through the forest,
Scooping up the field mice, and bopping them on the head,
And down came the good fairy, and she said,
"Little rabbit Foo Foo, I don't want to see you
Scooping up the field mice, and bopping them on the head."

Little rabbit Foo Foo is given 3 chances by the good fairy to reform, on pain of being turned into a goon:
I'm going to give you three chances
And if you don't obey me
I'm going to turn you into a goon!

Three days go by (repeat the song and actions each time) and Little Rabbit Foo Foo is unreformed. At the end, Little Rabbit Foo Foo is indeed turned into a goon by the good fairy.

I'll leave the moral to someone else. Suffice it to say that Little rabbit Foo Foo is now pursuing a profitable career in the NHL, with European forwards substituted for the field mice.

A regional variant is Little Bunny Foo-Foo.