Other source:
Goku throws a giant boulder at Gohan to test his abilities with the Z Sword. Gohan makes a clean cut, so Shin conjures up a block of the hardest metal in the universe. This time, the sword can't cut it, and breaks under the pressure. But from out of the Z Sword comes the Elder Kai, who is fifteen generations older than Shin. In exchange for a date with Bulma, the Elder Kai agrees to awaken Gohan's sleeping powers. He starts to do a strange dance in circles around the Saiyan, and says that it will take 25 hours to awaken his sleeping power. Meanwhile, Trunks and Goten have finally mastered the Fusion Dance, and are ready to attempt it for real.
