o

o means oh most of the times, but it's also used for unfinished ok.
o can also mean ooo (amazed)
short o means wha-

(yes people use this)

Girl 1: I still didn't find any sources of that picture

Girl 2: o
Girl 2: :(
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Girl 1:I found a really good profile picture!
Girl 2: o
Girl 2: Cool
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Girl 1:(shows a weird deep web youtube video)
Girl 2: o...