The definition of the colloquial-expression oo-roo?

"Oo-roo" is not a commonly recognized colloquial expression in English. It's possible it's a regional slang term or a made-up word.

Could you provide more context?

For example:

* Where did you hear this expression? (Specific region, country, group)

* What was the context of its use? (Conversation, written text, etc.)

* Can you give an example sentence?

With more information, I might be able to help you figure out the meaning of "oo-roo."