Saying something nasty and following it with “I’m just joking” is a form of verbal abuse that’s passive-aggressive. I.e: it’s semi-concealed aggression, intended to give the target pause as to whether or not they can successfully counter-attack.

Is this the right room for an argument?
It’s a technique that can be employed in a strategy of verbal abuse but succeeds if it’s fairly consistent, and only then against unsophisticated targets.