Goku and Gohan both combined their Kamehameha's and blew Cell to a beautiful oblivion. Well, to make it more understandable, Cell was gonna self destruct, but then Goku used the Shukkan Idou and teleported to Kaiou-sama's planet. Then Cell exploded and Goku, Kaiou, Bubbles, and Gregory were taken with him, but since there was that lump in Cell's head, he was formed back into Perfect Cell again. When Cell got back to Earth, he decided to kill Trunks, and then Vegeta got so pissed and attacked Cell, which was pretty stupid. Then Gohan didn't know what to do, and then Goku spoke to him and had a family moment and did the Kamehameha, yada, yada.