Goosebumps: The Blob That Ate Everyone (1997)

Dreaming of becoming a big-time writer, young Zack comes across a strange old typewriter and begins composing a horror story about a voracious pink blob monster -- only to discover that every word he types comes true. When the creature gobbles up the magic typewriter itself, Zack must figure out how to get rid of the beast in this episode from the spooky kids' series.