Dragon Ball Z

Synopsis

Now back in control, Buu toys with Goku, telling him he has some time to find someone to fuse with. He considers fusions with Dende and Hercule, but neither of them are appealing possibilities. He suddenly senses that Vegeta has returned, and uses Instant Transmission to teleport to his location. While Buu is distracted, Dende heals Tien. After Goku finds Vegeta, Goku tries to convince him to fuse, but Vegeta is angry at Goku because he knows Goku was holding back his Super Saiyan 3 transformation when they fought. With Vegeta refusing to cooperate, they are forced to take on Buu as individuals, but are clearly outclassed. Goku tells Vegeta that Buu absorbed Trunks and killed Bulma and asks him to put their differences aside to save their people. Vegeta finally agrees, and only when he puts the earring on does Goku mention that the fusion is permanent. The two last surviving Saiyans fuse and a new being is created.

(Source: Wikipedia)