1 Noun: a turtle, a tortoise, or any chelonian
2 Noun: the sound that turtles and otherwise make, (historically as they fly through space, rev. to any sound a turtle makes)
3 Verb: the act of creating this sound. past tense "Maroooed" Present part. "Maroooing".
Maroooo can contain any number of Os, but usually between two and four, never one. The amount of Os appropriate depends on the speaker/writer.
"Omg hurry up! Don't be a maroo!"
"*leaps off cliff* MAROOOOOOO!!!"
"*launches turtle into space* Get Marooooed B!%(h !"