Goosebumps: The Girl Who Cried Monster - R. L. Stine

Lucy likes to tell monster stories. She's told so many that her friends and family are sick of it.

Then one day, Lucy discovers a real, live monster: the librarian in charge of the summer reading program.

Too bad Lucy's told so many monster tall tales.

Too bad no one believes a word she says.

Too bad the monster knows who she is...

... and is coming for her next.