This word was made up by accident and it sounded good so people say it alot. Just like from Seinfeld when they made up "Yadda, yadda, yadda!"
This word can mean LOTS of things.
If someone says..."do you want fries with that?" just say "Monamana!!!" or if someone says "Fu%k you!" just say.. "Monamana!!!" and they will probably shut up. it can be used as a
NOUN, "thats my Monamana!"
VERB, just say the word
ADJECTIVE, "it kinda looks like a manamana!"
oh, and use this word sparingly!