You live your entire life as a criminal in a desert. The only companionship you have a talking cat. One day, desperate for something of worth in your dirt-ridden existence, you try to rob a teenage girl, a pig, and a small boy. The small boy kicks your teeth out after seeing a girl makes you bashful and embarrassed and you pass out.
When confronted with the possibility of having any wish granted by a magical dragon, your wish would be "I don't want to drop spaghetti while looking at a lady."
You then spend days creeping on these folks, watching for a way to achieve this lofty goal, you are forced to hit a little girl (one of your few [only?] victories) and then hit on her.
Eventually you are captured and saved only when the little kid turns into a giant monkey. The pig does more than you to save the day.
But it's okay, right? You finally got a girlfriend. Well, kind of. You don't really see each other that often.
You decide to show the world your stuff and enter into the Tenkaichi Budokai, the greatest martial arts tournament of all time. You are immediately eliminated in the quarter finals by an old man nobody's heard of before. You embarrass and humiliate yourself by insisting that it's a different old man in disguise before being proven a fool.
The next time you hear from Goku, he's taking on terrorist Nazis or some crazy shit. So you gear up to raid the Hydra base and... you're not needed at all. You get a sinking feeling in your heart, like this won't be getting old soon.
You help Goku fight the fortune teller's fighters. An invisible man beats you up and you barely win when your girlfriend is gawked at by an old man. You are then beaten up by a mummy.
But the Turtle Hermit, greatest living martial arts master, has taken you in. You'll do well in the next tournament!
Nope. The heel you challenged beats and destroys you in front of a crowd. You are helpless. Like a child. Your legs, broken. By the end of the tournament, the man who brutalized you is declared champion, but he decided to be "nice" now, so you have to pretend that it's okay and you're friends after he annihilated your pride for all to see.
A demon king attacks the world and you stay with the peanut gallery. The bad guy doesn't even bother to go after you despite specifically targeting martial artists. Jesus Christ.
Speaking of God, Goku is training with God now. You feel so very small and weak. M-maybe the next tournament.... ?
The next tournament sees you headbutted in the junk and defeated handily by a middle aged tourist. True, it's God in disguise, but still. Nobody knows that. Yamcha, the desert bandit. His tournament career ended by an old man. That's your public legacy.
(Also you have a scar for some reason, which is kind of pathetic considering that the children who underwent the same training didn't get maimed like you).
Oh, and Goku gets married before you, and he doesn't even know what marriage is.
Years pass and you become a baseball player. That one glorious period of fame and recognition is going to come to an end. You learn that Goku's dead and it's time for you and the others to take the lead. Time to train under God himself to protect the Earth from deadly aliens.
Nevermind, you died. Krillin destroys several saibamen with a single attack, while you lie lifeless in the dirt. good try though. Yajirobe and the five year old do more than you.
For the next few months you sit on a planet while King Kai teaches you jack shit.
You come back to life! Your girlfriend breaks up with you and immediately starts flirting with the guy who got you killed less than a year ago. His power is so strong and big compared to yours, flaccid and tiny. You can only stand around and cry when Frieza comes to Earth, and are filled with joy when he's defeated by a mysterious stranger from the future who gives you a dire warning that you're going to fail in another timeline as well.
After three years of training your ex hooks up with the evil spaceman and they make a baby, who you have to help change the diapers of whenever you swing by.
You get punched through the chest by an old man without doing anything. You try to explain that they can steal your energy, but you could have done something before that. You just don't care anymore. You wait until Goku's nearly dead to explain the energy stealing bit, and then take him back home to babysit him as you openly acknowledge your uselessness.
Oh, and the future stranger is Bulma and Vegeta's badass robot fighting son, and thus the whole fate of two worlds depended on Vegeta and Bulma's amazing sweaty unprotected lovemaking. Nothing has ever depended on you or ever will.
Tien does more than you when he holds off the bugman. You just do nothing. Krillin gets a robot girlfriend who barely ages. You get nothing.
A tournament comes around again and the gang is getting together for old time's sake. Even Krillin is going to enter. Good ol' Krillin. Always there for the team. Always in the fight, even when he's outclassed.
You stay in the stands with Krillin's daughter to babysit her. Your ex-girlfriend cheers on her husband and their son, who wins the junior division. You have no son.
When they all fly off to fight Majin Buu, nobody even thinks about inviting you to come and help.
Nobody ever thinks about you.