Romans considered "onos" a negative attribute, like Odysseus' intelligence, and it became transmuted into the less-positive "onus," or "burden."
"Ron, it's the pancake breakfast. We do it every month."
"O No. Ron's ditching us again." You ought O No he would pull this.
Bret's girlfriend Coco, "Flight of the Conchords
x:you take care talk to u later
x :o n o
This is used to end a conversation usually in a instant messaging situation, possibly may be used in a non-real-time communication method such as E-Mail.
This normally is the last thing one says after "bye", "cya", "pce out", etc. It's a way to stop un-ending exchaning of "Bye"(s) at the end.
Person 2: sure, and don't forget the home-work !
Person 1: yea ok bye now
Person 1: ono
Person 2: ok bye cya
Person 2: HEY what page is the homework again ?!
Person 2: HELLO ?!? You there ?!
Person 2: :S