Put me in a Book by Robert Munsch, illustrated by Michael Martchenko

From chapters.ca:
On their way home from a field trip, the class meets a famous writer who says he is looking for a kid to put in a book. Hailey volunteers, so the writer flattens her out, folds her up, and stuffs her in. But Hailey feels folded and scrunched and trapped and stuck, and asks the kids to get her out of the book. They try all kinds of things, but nothing works, until finally they have an idea - and turn the tables on the famous writer!