SPOILER WARNING: The following article contains minor spoilers for IT Chapter Two.
The loudmouth kid happens to be particularly freaked out by movie monsters like The Mummy and The Wolf Man, and so IT takes their shape to feed on his fear.
It’s an element of the story that only sort of found its way into the first half of director Andy Muschietti’s big screen adaptation, but that lacking is made up for in IT Chapter Two with a fantastic nod to John Carpenter’s 1982 masterpiece The Thing.
In Stephen King’s IT, some of the forms that the titular evil being takes when he is tormenting Richie Tozier are taken directly from horror movies of the era.