Captain Underpants and The Attack of the Talking Toilets by Dav Pilkey (Part 1)

"We can do whatever we like, " snarled Mr. Meaner as he dashed over to the gymnasium door. "Look, I'm opening the door!" He quickly opened the gym door. "Now I'm closing the door," he said. "Now I'm opening the door again, and now I'm---AAAAAAAAAHH mmblemble gluh!"
An evil toilet had stuck his mouth through the door, snapped Mr. Meaner up, and swallowed him whole! "Flusssssh!"
(Pg 64)