Mockery on its own is really immature, but when used as a tool to get something out of your partner, mockery is a sign of aggression and irrational need for dominance. Humor should be funny. It should not be about joking at the expense of another human being. This type of humor can often be found in disrespectful and abusive types of relationships.
Making fun of a partner is demeaning especially since this type of humor usually includes some type of not so shiny truth directed at the partner. People who feel good about themselves do not need to make other people feel bad to make themselves feel better. That can be a sign of emotional repression or a bad upbringing. In any case, most bullies only need someone to give them their a piece of own medicine by acting in a way that they are acting in order to make them stop.