The Strongest Man in Other World
(Until he's retconned out of that position.)
When Kaio-sama introduces himself to Son Goku, who at this point thought Kaio's pet monkey Bubbles was the real Kaio, he did so with a play on words... Slowly turning "mosquito" into "Kaio". What this means for Goku becomes clear immediately after Kaio makes his next joke...
"Hello? Hello? Huh? I picked up the phone, but no one was home."
When Goku doesn't laugh at Kaio's pun, he refuses to train him.
(Masako Nozawa's Goku fake laugh here is hysterical.)
With that sorted, Kaio-sama agrees to teach Goku... but only if he can think of a clever pun and make Kaio laugh, first!!
"My futon... flew away, gone...!"
"My feline... has gone supine!"
"My stylist is sightless!"
Winner and twice runner up at the Tenka-ichi Budokai, the single-handed eliminator of the Red Ribbon Army, savior of the world and defeater of Piccolo Daimao... and now, master of stupid puns. At last, Son Goku's training can begin.
Of course, Kaio-sama thought he came to be trained in the ways of comedy. "What, you want to learn martial arts? Why didn't you say so sooner?" Given how slow and weak Kaio's planet makes Goku, as a person from Earth, Kaio first assigns him to catch Bubbles!! Goku is worried about the Saiyans arriving on Earth soon, and Kaio confirms they will be there in 158 days. But training for that long with Kaio-sama will be like a thousand years on year! (Not literally in the Room of Spirit and Time sense, but because of the gravity and because Kaio is boasting.) But in order to defeat the Saiyans, Goku must surpass Kaio-sama!!
With the weighted clothing given to him by Kami-sama, Goku can barely move, let alone keep up with the spry Bubbles-kun!
So off they go, and off goes Goku!
But he's still unable to catch Bubbles, and decides to take a break for food.
"Taste aside, at least my stomach is full!"
"I get the feeling that maybe this man isn't giving me enough respect."
Goku is surprised Kaio-sama doesn't get bored living on such a tiny planet. Kaio says that to a mature mind like his own, it is easy to find stuff to do!
Counting blades of grass.
Looking at the sky.
And of course...
Going for drives.
Kaio sends Goku back after Bubbles, but this time with his weighted clothing. He explains that the Saiyans' home planet had gravity about equal to his own, which is part of why they're so strong. The other reason being their extraordinary fighting instinct, making them incredibly formidable.
"Hey, that's fine! I'm a Saiyan, too!"
Meanwhile, Gohan is fast improving in training under Piccolo..!!
That night, Gohan asks Piccolo about his fight with his father. Piccolo tells him that once the Saiyans have been defeated, he will finish Goku next. But Gohan sees through Piccolo's pretension. His dad told him that the reincarnated Piccolo isn't as bad as the old Piccolo Daimao, and Gohan reckons he's right, even if his mom and grandpa are still afraid of him. Furiously, Piccolo tells him he'll have even harsher training tomorrow!!
"Damn him, anyway..."
Three weeks go by, and finally...
Goku catches Bubbles!!!
Kaio is very impressed... and thinks this man might be able to master it...
The Kaio-ken Technique!!