Herm. I thought it was just fun-sounding. And maybe in some song lyrics? [Quick google check] Wow, it's hard to get any search results that aren't just about the pony, but I think this is the song I'm thinking about- it's the chorus from "An Irish Lullaby", same one 3377345 linked to:
"Too-ra-loo-ra-loo-ral, Too-ra-loo-ra-li,
Too-ra-loo-ra-loo-ral, hush now, don't you cry!
Too-ra-loo-ra-loo-ral, Too-ra-loo-ra-li,
Too-ra-loo-ra-loo-ral, that's an Irish lullaby."
A little creative license on the name, Toola Roola instead of Toora Loora.