The Schwa was Here book By Neal Shusterman

Anthony, also known as "Antsy," is fascinated by "The Schwa Effect"--the fact that no one ever sees Calvin Schwa. Even when acting weird and dressed like a total freak, The Schwa is only barely noticed. The two boys form a partnership and get away with all kinds of mischief, from conducting experiments at school to confounding opponents on the basketball court. When The Schwa senses that even Antsy is beginning to lose sight of him, he vows to do something that will make him so visible, no one will ever forget him. Any kid who's ever felt unnoticed will identify with Schwa and Antsy and their quest for notoriety.