How did ender provoke Bonzo?

Ender is alone in the shower, and his absence from the Commanders' Mess is noticed. Seven older boys, led by Bonzo and including Bernard, enter. Ender calls on Bonzo's honor to trick Bonzo into telling the other boys to let him fight Ender alone--who would need six friends against a naked boy? Bonzo protects his honor and strips naked to even the playing field.