S1·E23 "Hisoka × Crash × Gon

Gon gets Hisoka's number badge while Hisoka kills an examinee crossing his path. Gon is poisoned by Geretta and relieved of his badges. Hisoka kills Geretta easily and returns both badges: Gon's and his own. Gon tries to refuse it, but is unable to. Hisoka tells Gon he will kill him when the time is right, until then he will protect him. He punches him in the face and tells that he can return the badges only after he can return the punch.