Internet slang for awesome. Awe was shortened into a
single 'O' and some was changed into sim for a shorter pattern of
letters which, when arranged and verballed expounded produces a
sound entirely similar to the original word.
Ricky: That's osim
mate, good job.
Derek: Yeah, it was
pretty awesome, I'm just glad I pulled it off in
time.
Ricky: I hear ya, I'd never be able to in that timeframe