This is a request story from Greymon Leader. Hopefully, you will like it. (Note: All idea credit goes to Greymon Leader.)
Disclaimer: Thankfully, I do not own Dragon Ball, otherwise, it would be the worst show in the world. Gogeta Gotenks
(Goku's place)
"NUH-UH!" Goten yelled, clenching his fists in protest.
"YEAH-HUH!" Trunks yelled back as he narrowed his eyes at the shorter boy.
"There's no way I'll ask that! They wouldn't do it anyway." Goten claimed, raising his index finger up, trying to look wise.
"You never know unless you try." Trunks stated with a sly grin.
"Fine! I can't believe I'm doing this." Goten gave up and walked towards his father and Vegeta.
Goten gulped nervously, slowly inching his finger forward to poke Goku's shoulder. Finally, he poked him, and caught his dad's attention.
"Oh hey, Goten! What's up?" Goku asked in his usual nice tone.
"W-well.." Goten tried to answer, but Vegeta's cold glare stopped him from speaking normally. "Can I tell you in private?"
"Mm, I guess." Goku shrugged and followed his son to the kitchen.
(In the kitchen)
"So what is it, kiddo?" Goku asked, slightly curious.
"I...I.." Goten tried to answer, but the words just wouldn't come out.
"Goten, if you have nothing to say-." Goku said, but got cut off by Goten.
"Can you, me, Vegeta and Trunks have a fusion battle?" Goten asked in a begging tone as he smashed his hands together to make it a more effective begging stance.
"Goten..I don't think Vegeta would do it. I mean, he's Vegeta! Think about it." Goku reminded with a slight sigh.
"I know! But if you anyone can convince him, it's you. Or Bulma." Goten added, hoping to change his father's mind.
"I guess I can try." Goku huffed.
"Yes!" Goten cheered.
"But don't expect him to say, "yes", okay? He is Vegeta after all, and the only way now to do a fusion, is that dance-like thing." Goku stated, remembering himself, that Vegeta would never, in a million years, dance!
"I know, I know! But good-luck anyway!" Goten exclaimed and happily rushed to Trunks.
"Now how am I going to do this?" Goku questioned himself as a comical sweat-drop befell on his forehead.
(Back to the living room, where Vegeta was)
"Heyyy, Vegeta. Just the man I wanted to see!" Goku chuckled nervously. He couldn't believe he was doing this!
"What do you want?" Vegeta asked knowingly. Goku had to have wanted something from him.
"Want to get more powerful?" Goku asked with a slightly nervous tone.
"YES!" Vegeta shouted and instantly got up from the couch in excitement.
"Oh..okay. Well, follow me!" Goku guided Vegeta, and did the "thumbs up" sign to the boys to show Vegeta was on board.
The two boys scrambled giddily and followed them to the place where Goku convinced Vegeta to get more power at. So as soon as they got there, Vegeta asked Goku how to get more power.
"Well..you have to do one little thing first." Goku replied worriedly and obviously Vegeta asked what it was. "Just do what I do."
"Okay?" Vegeta nodded, but his eyebrow cocked questionably as he saw Goku..dance? At least he thought it was a dance..wait! This looked far too familiar..is this..what he thinks it is?
"Goku! Is this the fu-." Vegeta tried to ask, but immediately got interrupted by Goku.
"JUST DO WHAT I DO! And you will get stronger." Goku interrupted Vegeta abruptly and continued doing the fusion.
Vegeta blushed a deep red, finally realizing what was going on. Though he held back his pride and did what Goku did, to get stronger. He just couldn't let that cocky guy get even stronger than him! So he went along with Goku, and they did the fusion. Soon afterwards, Goten and Trunks did the same thing, and smirked at their opponents.
"Good job, dad!" Gotenks smiled brightly as he "thumbs up'd" his dad.
"Yeah, it was pretty easy." Gogeta grinned proudly, angering the Vegeta "inside" him.
"Anyway! Let's fight!" Gotenks yelled and charged at Gogeta in a straightforward manner.
Gogeta's eyes widened in surprise at the sudden charge, but they quickly retaliated and dodged the mild blow. Gogeta swiftly kicked at the younger duo, forcing Gotenks to fly in the air and fall flat on the ground. Though, the "Goku" inside Gogeta made the hit very mild for the kids. Gotenks got up as quickly as possible to not get hit again. The hit from Gogeta didn't hurt, Gotenks could tell that Goku went easy on him.
"Dad! Don't go easy on me, this is a match!" Gotenks shouted and kicked him as hard as possible, making Gogeta fall backwards.
Gogeta nodded in reply and began fighting back, fist and fist. Gotenks dodged the hard hits and kicked the vulnerable side, making Gogeta fall down. But Gogeta quickly jumped up and double-kicked Gotenks in the face. Gotenks instantly fell face-flat onto the ground.
"You okay?" Gogeta questioned as he grabbed Gotenks's hand and pulled him up.
"Yeah.." Gotenks grinned and kicked Gogeta in the "coconuts".
"GAAAAAAAAAAAAAH!" Gogeta screamed to the heavens as his privates were smashed by a rather strong foot.
Finally, the two fusions turned back to normal, and Goku and Vegeta held their coconuts in pain.
"Trunks! That was dirty!" Goten yelled angrily. He didn't want to do such a dirty move to win. He was after all, Goku's son.
"But we won, didn't we?" Trunks smirked proudly, complete un-deterred by his dirty trick.
"TRUNKS!" Vegeta shouted as held his coconuts, and ran after his rushing son.
"CRAP!" Trunks shrieked hearfully as he ran as fast as could to his house.
"Dad? Are you okay?" Goten asked with concern as he looked down at his father.
"Goten...carry me...I need..ointment.." Goku muttered painfully, and Goten distastefully carried his father home, wondering why his father needed ointment..
I wrote this in a hurry, due to the fact that I was extremely busy, so I'm sorry if I messed up at all. But, I hope you like it, Greymon Leader.
Also, I'm not very good at writing fight scenes yet, so I apologize for that. And that's also why I finished it up with the ol' kick to the groin scenario. xD