bash (something) against (something)
To smack something against another surface. Billy went to the nurse after he bashed his head against the low ceiling in the art studio. He bashed his guitar against the amp and it splintered apart.
bash something against someone or something
to strike something against someone or something. He accidentallybashed his head against a beam. She bashed her sore elbow against Ted's forehead and both of them were hurt.