It wasn't really scary, don't know why it was a Goosebumps book.
You Can't Scare Me! (Goosebumps)
By R. L. Stine
Eddie and his friends plan to dress up as the slimy Mud Monsters--legendary spooks who supposedly live in Muddy Creek--but their plans change when they meet the real Mud Monsters.
Publisher: Apple
ISBN-13: 9780590494502
ISBN-10: 0590494503
Published on 8/1/1995
Binding: Paperback
Number of pages: 120