bash (someone's) brains in

To strike or assault someone violently and severely, typically on the head, such that it may cause the person severe injury or death. Primarily heard in US. I warned her that I was going to bash her brains in if she didn't stop insulting me. They left him to die after nearly bashing his brains in. Even if the police never catch them, the thugs that robbed that old man and practically bashed his brains in will rot in hell!