take someone over one's knee
打某人的屁股
A:The answer is zero! What a let down!
A:白忙了,真让人失望。
B:I really want to take him over my knee.
B;我真想打他的屁股。
A:No hard feeling. After all, he is a child.
A:别生气啦,毕竟他还是个孩子。
B:If you say so!
B:既然你这么说就算了吧。