Over and Out
Even though "OO" is used to say "Over and Out" as in "goodbye" it is actually not correct usage because "over" usually means "it is your turn to respond," and "out" usually means "we're finished and I'm out" as in, "I'm no longer texting or listening." FYI.
Online jargon, also known as text message shorthand, used in texting, online chat, instant messaging, email, blogs, and newsgroup postings, these types of abbreviations are also referred to as chat acronyms.For the largest list of Internet acronyms and text message jargon, click on "more info" below!
NetLingo Classification: Acronyms and Text Message