There's a Boy in the Girls' Bathroom — Louis Sachar

"Give Me a Dollar or I'll Spit on You.

That's Bradley Chalkers for you. He's the oldest kid in the fifth grade. He tells outrageous lies. He picks fights with girls, and the teachers say he has "serious behavior problems." No one likes him -- except the new school counselor, Carla. She thinks Bradley is sensitive and generous, and she even enjoys his farfetched stories. Carla knows that Bradley can change, but Bradley isn't so sure.

Sometimes the hardest thing in the world is believing in yourself.