DBZK Episode 6
From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
The End of Snake Way! King Kai's Bizarre Test! is the sixth overall episode in the Dragon Ball Z Kai series. The original Japanese title is "Tadori Tsuita Shūten! Kaiō-sama no Ochame na Shiren" (辿り着いた終点!界王様のおちゃめな試練). The episode first aired on May 10th, 2009. It's original American air date was May 26, 2010.
Six months have passed since Gohan's incident with the full moon, and he has since become much more adept at surviving in the wilderness. Piccolo then decides to begin training the boy personally. Meanwhile, Goku has arrived at the end of Snake Way, meeting King Kai on his planet, which, despite its small size, is 10 times Earth's gravity. In order for Goku to train under King Kai's teachings, he must attempt to make the master laugh. After Goku's accomplishment of making him laugh, King Kai tells him to catch his monkey, Bubbles. Having Bubbles run around his planet, Goku must chase after the monkey; a difficult task for him due to the planet's heavy gravity.
- Watch this episode at 4Kids TV