It's mean to point out someone's flaws.
Curt is hanging out with his friend, Art, who has a noticeable stutter.
Curt wants to talk to Art.
Curt tells Art that he'll stick up for him no matter what.
Curt tells Art that his stutter makes him sound like Porky Pig.
Art feels supported and doesn't have to think about his stutter as much.
Art's feelings are hurt, and he comes self-conscious about his stutter.