It hurts alot when he hits me?

so theres this guy who randomly punches me or shuvs me or gets im my way when im walking in the corridor. Sometimes when he punches m and then grins at me it hurts really really bad i get annoyed but he thinks im just playin. im gettin really frustreated. ttomorrow i have tosit next to him in alesso n and he is probz going to do it again. oh and i call him a wimp sometimes and make fun of his musles is that why he hits me hard? he gets into a lot of fights so he isnt really a wimp and he knows i know that. Thnx : )