My ex NPD never stopped taking the p##s out of others, he could be very funny singling out peoples quirks and mimicking them. In small doses its OK, and he never went too far with people bigger than him hes not that stupid.
He was however a nightmare to live with, constantly ridiculing, belittling, spiteful, a 'shredder' of others.
He would pick me to pieces endlessly, but being a narc if I retaliated in any way no matter how mildly guess what? NARC RAGE how dare I, indignation, anger, aggression even violence so great was his narcissistic injury.
Why did he do it, in his case I think it was because he was insecure, he had never matured into a adult he was, and always will be a spoilt, greedy, demanding, spiteful, self absorbed toddler.
The journey of a thousand miles begins with a single step.