smash (one's) face in
To strike one in the face or the head with intense, violent force. The cops arrested the man after he threatened to smash their faces in. Where's the guy who insulted you? I'm gonna go smash his face in!
smash someone's face in
1. Fig. to crush someone's face. The accident smashed Harry's face in, and he had to have extensive surgery. The accident smashed in his face.
2. Inf. to strike someone in the face. You had better stop that or I will smash your face in. Max tried to smash in Lefty's face.
smash somebody’s ˈface/ˈhead in
(British English, informal) hit somebody very hard in the face/head: Give me the money or I’ll smash your head in.