Generally has the same meaning as "omg" or "oh my god/gosh". omfqis also an acceptable form. Can be used positively (1) or negatively (2).

Originally used by the Seattle-area famous Elize Papineau, and has now spread all over the internets via AIM, LJ, myspace, etc.

Put simply, Ruobing is the greatest being in the known Universe (Most likely, the greatest in the unknown Universe too)
Ruobing can mean anything (Anything that is good of course) and Ruobing can own you (1 hit ko, critical hit) in 0.1 seconds