It is a person who talks about stuff which does not interest his audience. Somebody who speaks of nonsense. Moopers are commonly found in offices with management positions. etymology: mo - mouth oper - from pooper, pooping (crapping)
Ulzzang true definition is "best & "face" = best face in korean. They are basically people with above average looks, sometimes with the use of photoshop and haduri who post their pics online, some becoming internet celebrities.
"Hey, see that chick over there? She's pretty enough to be an ulzzang. :D"