Meaning knob, but more effective, long and drawn out when used as an insult.
Pioneered by chaucer in his canterbury tales which included such choice lines as "the knight had he a smalle knob" (or something like that). Anyway, those crazy olde english cats pronounced the Ks and kernob was born.
Particularly effective when used after the target has just left - look at your remaining chums, roll your eyes and destroy them in one word (two syllables mind- emphasis should be on 1st syll obv). Ter-wat is also used but not quite as effective
Luke: *blah blah blah blah blah* (talking crap)
Laura: I think you're wrong
Luke (angry): I don't care, fuck off
Laura: 1 word, 2 syllables....
Luke (sarcastically): ummm, oooh, im not sure what u could be about to say...!? stop using that stupid word it'll never catch on (stomps off)