It is not funny to use physical violence against another.
Joe was being mocked by Billy, another kid in his class.
Joe wants Billy to stop mocking him.
Joe gets a jokebook and tells jokes right back at Billy to make fun of him.
Joe punches Billy in the face as hard as he can next time he makes fun of Joe and laughs at him.
Joe eventually hurts Billy's feelings with his jokes, and he stops making of Joe.
Joe got detention, extra homework, and grounded for a month, although Billy never made fun of him again.