The Legend of Goku (S01E13)

Once again, Pilaf has taken Goku and his friends captive. That evening, as Goku gazes at the full moon, he uncontrollably transforms into an Oozaru! In his frenzy, he breaks free from their prison, allowing Yamcha and the others to escape. However, Goku, now in a wild state, continues his destructive rampage. To stop him, Yamcha bravely severs Goku’s tail, which reverts him back to his normal self. After regaining consciousness, Goku and the group vow to meet again as they go their separate ways.