"The Strongest Man" (最強の男編 Saikyō no Otoko-hen) is a special bonus chapter for Dragon Ball SD.
Summary
At Saikyō V-Jump Festa, Bulma is trying to explain the idea of a convention-type event to Goku when they hear shouting. Sai Jack, the official mascot of Saikyō Jump, is working the crowd and getting them fired up, but Goku interprets his words as a genuine challenge and decides to see just how strong he is. The poor guy doesn't stand a chance…