You shouldn't say hurtful things to your friends.
Greg is a high school student.
Greg wants to be more popular in school.
Greg joins a sports team the popular kids are on and spends time with them.
Greg makes fun of the nerdy friends he has to fit in with the cooler kids.
Greg has more friends than ever and is seen as a nice guy.
His nerdy friends ditch him and Greg is seen as a jerk, and his new more popular friends ditch him for someone more like themselves.