pound head in
pound (one's) head in
To give one a severe, violent beating (not necessarily solely on the head). The police officer threatened to pound the man's head in if he didn't stop resisting arrest. You watch your mouth, or I'll pound your head in!
pound someone's head in
Fig. to beat someone, especially about the head. Fred looked like he wanted to pound Mike's head in; he was so mad! You want me to pound in your head?