It is mean to stop talking to your mother
Phil was grounded by his mother for his report card, which Phil claims was wrong.
Phil wants to get revenge on his mother for the unfair punishment.
Phil continues to insist that the report card was wrong and refuses any punishement.
"Phil refused to talk to his mother at all, only giving silence and listening to instructions other than ""talk""."
Sure enough, the school calls to inform his mother that his report card was for another student named Phil.
Phil succeeded in hurting his mother's feelings but that only keeps him grounded longer.