One Day at Horrorland (Classic Goosebumps #5) by R. L. Stine

Werewolf Village. The Doom Slide. The Coffin Cruise. These are just a few of the terrifying attractions that await Luke and Lizzy Morris at HorrorLand. Step right up and join the Morris family as they ride each ride--and scream each scream--for the very first time. Because it might also be their last.