usualy said by a bloke when asked a question. any question as a matter of fact.
it can also mean the following:
err no way!
Girl: Do you have a crush on me?
The sound made when something absolutely amazing happens, (cumming on a girls face, doing a perfect headshot on CSS, getting a hole-in-one in golf), to perfect this sound you must have a fairly deep voice and put all your power into it until your throat hurts!
Rob: Finally fucked that girl Alex last night, as i cummed over her tits i let out the greatest 'UMMM!
' ever, i'm not gonna lie, IT WAS GOOD!
Adam: Thats what i like to hear!
The response to a question that you know the answer to but don't want to admit, the response to a question you don't know the answer to or just a response to piss someone off.
"Can you help me reformat my hard drive?", ummm...