Captain Underpants by Dav Pilkey

This book is about two boys named George and Harold being bored at school and make comic books. They had a horrible principal named Mr. Krupp. George found a 3D hypno ring and hypnotised Mr Krupp and obey George and Harold. Mr. Krupp turned into Captain Underpants. He was fighting crime. George and Harold said don't snap your fingers in front of Mr. Krupp.