I need some help on this one !! please help !

First horror movie ? :confused:

- I was still living in mexico, and I was first introduced to a VCR when my older brother, Saved up 4 of his paychecks to buy one....
Not sure if you guys remember, but they were expensive as heck in the early 80's.... My brother bought it as an investment, lol ...
he made a mini-theater at my house, in his big ass room !!. Well to make my bullshit story short, he had a Movie schedule ....Monday--Action Tueday--Martial arts Wed ---Sun ..PORN, j/k. .. HORROR movie day was on saturday... And me being the youngest one, I was not allow to watch horror movies....Or my mom would close down the theater lol , well, one day I freakin cry, and cry till they finally let me watch my first horror movie. My ?? ...I dont remember the name, But It was about a group of High school or College students who used to pick in a fat kid, everybody made fun of him........Till one day I'm not sure but he goes to a big house / school building and he starts praying the devil. " not sure but I think he kills a pig and offers it to the devil". He get's some evil powers,,,, And he kills most of the people who were making fun of him... The thing that scared me the most was when he ""gets off the ground and He starts floating forward as he was posses, and kills a lady, i think a teacher. Well thats all I remember!!! hope you can help me find the name of this movie... If you do, I'll give you my 2cents ..j/k

---There's a reward if you find out the name :) :confused: