Last Word Syndrome
A compelling need to be the last person to speak during an argument or conversation; finishing an argument with a response of immaturity typically consisting of either repeating the last thing you said over and over until the other person stops talking, making whiny/baby noises, or childish name-calling.
Person 1: You're such a tool.
Person 2: I'm not a tool. I work because I have goals for myself and I don't mind working hard to achieve them.
Person 1: You're a tool.
Person 2: You just said that.
Person 1: You're a tool.
Person 2: Think you've got some last word syndrome, buddy, later.
Person 1: *Shouting after you* Whaa, why don't you cry about it?
Person 2: I'm not a tool. I work because I have goals for myself and I don't mind working hard to achieve them.
Person 1: You're a tool.
Person 2: You just said that.
Person 1: You're a tool.
Person 2: Think you've got some last word syndrome, buddy, later.
Person 1: *Shouting after you* Whaa, why don't you cry about it?