R.L. Stine 
Rotten School #7: Dudes, the School Is Haunted! [EPUB ebook] 

Joe Sweety is the worst kind of bully — big, mean, and always ready to use his fists. Chipmunk is the shiest, clumsiest kid at Rotten School. When Chipmunk is paired with Joe on the class trip, things get ugly — and fast! Chipmunk spills his apple juice on Joe, he barfs on Joe, and he pulls down Joe’s pants. All accidents, of course. But does Joe care? No way! He is out to get Chipmunk!Bernie Bridges can’t stand to see Chipmunk, one of his Rotten House guys, bullied by big, mean Sweety. So it’s payback time — and Bernie has a spook-tacular plan. It turns out that Sweety is scared of ghosts. Petrified! Bernie decides it’s time for the Haunting of Joe — with spooky messages on the computer, green protoplasm in his room, and a body-wrap in an eerie cocoon. Will Bernie’s payback work? Will it scare Joe into niceness?