negging

A backhanded compliment with an ominous twist, it's what manipulators use to undermine your confidence and therefore increase your need for that person's approval.

In the online dating world, according to Urban Dictionary, it refers to low-grade insults meant to undermine the self-confidence of a woman so she might be more vulnerable to a man's advances. For example, "I was wondering why that guy was complimenting me while putting me down. Now I get it, he was negging."