Gohan, son of DBZ's main character, was not taught martial arts at first, an insistence of his mother, but was still the son of a powerful man, and as such had great power within him. But for the longest time, he couldn't reach it on his own. However, a few times during the show, when he was really, really pissed off, he'd temporarily grow incredibly powerful. The first time was when he was crying, trapped in Raditz's spacepod, when he heard the cries of his father, got really made, smash the pod open, and slammed into Raditz head first. He almost immediately returned to normal, but it was enough for them to beat Raditz.