As one can easily see " ---O-O--- " represents a person wearing a pair of glasses..
Literally, you mention it when you want to call someone a geek or
a nerd(obviously as a term of
offence). But most of the time it its just used between close friends trying to pull a light
joke on each other. :)
Friend 1's (
Facebook Status) : " SPENT THE WHOLE FUCKING NIGHT DOING AN 3,000 WORD ENGLISH REPORT FOR
EXTRA CREDIT!! I'M FINALLY DONE!!! YESHHHhhh :) "
Friend 2 (comments): "hahahahaahhaha idiot you're
sucha ---O-O---..jk
:P"