[Bells]

Of course Jack would know what it really meant and its impact if he did say it. I think it shows his ignorance further if he did anyway.
Jack was not liked. He was hostile towards Shilpa for no apparent reason, perhaps to make Jade happy. Not to mention he was B-O-R-I-N-G with enough brains to fill an egg-cup (just about).
I reckon he was being more of a tw@t than racist. Because even if it was the 'C' word he said, that's hardly acceptable either when he said it for no apparent reason and nothing had been done to him personally!