捅刀子的少年你真善良

Translated as: 'stabbing boy, you're really nice', this seems paradoxical and contradictory at first. Actually, there is a cultural context behind. Generally speaking, in the Chinese context, the person described as 'knife-poke (捅刀子)' means betraying a friend's trust and doing harmful things behind the friend. But it seems this nickname wants to express a different meaning - praising this seemingly vicious act, perhaps implying the boy was pretending to harm others while actually helping. Alternatively, it may express irony or sarcasm.