Dragon Ball AF was the subject of an April Fool's joke in 1997 (following the end of Dragon Ball GT), which concerned a fourth anime installment of the Dragon Ball series. It has since gained a cult following, been the basis for various fiction and manga interpretations by fans, and has even resulted in a dōjinshi series produced by a fan by the name Toyble, and another manga made by a fan by the name Young Jijii. They don't work together in they're AF dōjinshis.
Toyble's Dragon Ball AF Story
Taking place after Dragon Ball GT, the story goes as far back to when Frieza was defeated by Vegeta, where it is revealed that Frieza's mother is the Western Supreme Kai (implying that she survived her battle with Majin Buu, despite being believed to have been killed). Apparently, Western Supreme Kai created Frieza with King Cold to create the ultimate warrior, but seeing Frieza defeated, she begins her search to find the one who had done this, showing little concern with her son. Cooler also appears with Frieza and King Cold.
Several years later, the world has been deprived of Goku and the Dragon Balls, but peace has been restored. Goten attends Orange Star University with his brother Gohan as his teacher and also as Great Saiyaman 3. When a scuffle happens in the nearby city, Goten checks it out and transforms to his Saiyaman state, finding Emperor Pilaf, Shu, and Mai doing a stick-up. Before Goten can do anything, a new superhero, Papayaman (actually Uub) arrives and easily dispatches of him. As Papayaman is praised by the citizens, Goten finds a survey that shows the town's "Top 100" favorite superheroes (in which we can see many characters from various Akira Toriyama's works), and finds himself being their least favorite. Disappointed, Goten heads home. Meanwhile, 2 Space Pods have landed in a wasteland, with the Western Supreme Kai emerging with her son, Xicor. The two immediately head to find Earth's Greatest Power and come across Goten, whom they nearly kill and cause a great shockwave around the whole planet. Gohan senses the power and comes to his brother's safety, questioning who Goten's attackers are. Xicor reveals himself as Gohan's brother and son of the Western Supreme Kai (implying that the Western Supreme fulfilled her goal to find Goku and somehow made love to him), greatly shocking Gohan. Vegeta and Trunks arrive as well to combat the invaders.
Xicor then demonstrates his power by destroying half of the Earth. An enraged Vegeta battles Xicor but despite his Super Saiyan 4 (we can notice that Vegeta didn't need Blutz Waves to transform this time) , he is no match. As Vegeta is pummeled, Gohan's tail suddenly appears and Gohan transforms into Super Saiyan 4 (he may got his tail back somehow and achieves this transformation while training). Super Saiyan 4 Gohan, Vegeta, and Super Saiyan Trunks battle Xicor but despite their combined power and Gohan's attempt to call Goku (due to Goku being in a sealed world, the attempt fails even though something had caught Goku's attention), they are ultimately no match for Xicor and waste all their power.
As they fought Xicor, in the sealed world Goku is in, Goku and Pikkon are training together, and as they spar, Goku is shown to have achieved the Super Saiyan 5 form. During his allies on Earth's struggle with Xicor, he manages to receive a small piece of Gohan's call, but due to being in a sealed world, Goku does not arrive. With all their energy exhausted, the heroes stand no chance for Xicor. However, before Xicor can act again, Kibitoshin appears and attempts to seal Xicor with the "Kai-Kai Divine Sealing Wave" into the Z-Sword, but the Western Supreme intervenes and manages to prevent the sealing. Before Xicor can destroy the sword, Gohan picks it up and attempts to attack Xicor with it, but is actually distracting him, buying time for Dende to restore Kibitoshin's strength. Kibitoshin attempts to seal Xicor once again and despite Western Supreme Kai attempting to interfere once again, they succeed.
An enraged Western Supreme Kai attacks the heroes but before she can undo the seal, Vegeta attempts to stop her. Even though Vegeta tires out before he can do any damage, the Western Supreme Kai was distracted long enough for Kibitoshin to sneak up on her with a surprise attack, bodylocking her. Warping into another planet, Kibitoshin self-destructs, apparently killing himself and the Western Supreme Kai, his sister, also known as Lila. The self destruction catches the attention of the heroes and even Piccolo in Hell. Including Goku and Pikkon in the Seal World, They were confirmed by Nuova Shenron (AKA Sì Xīng Lóng) that Kibitoshin is dead much to their shock.
Gohan mourns the death of Kibitoshin, but Vegeta tries have Gohan understand that he's making up for his personal mistakes. However their victory would end shortly as they noticed that the Z-Sword is starting to crack, They were telepathically informed by Old Kai that the seal has failed somehow. The seal will last for another month and when it breaks Zaiko will be free, Gohan believes that there's nothing that they can do but try to surpass him in one month and even if they try, it may still not be enough to stop the abomination.
Old Kai commended kibitoshin for barley doing a good job, thinking that such power couldn't be sealed away by one Kai. However, he speaks too soon when a dead Kibitoshin approaches Shocking Old Kai along with Tapion, Minotia, Sugoro and Shusugoro. Kibitoshin claimed that he had nowhere else to go, in which an angry and annoyed Old Kai scolded him for his actions.
The Z-Fighters are seen recovering (and Mr. Popo picking up an unconscious Dende), Vegeta begins to question who Zaiko really is and Gohan could only remember when he was still a boy, A long time while bathing with his father at the time and Goku revealed that Planet Yardrat was not the only planet he vistied, but another planet there he met a Princess and she supplied him with lots of food, after eating Goku began to fall asleep, giving the Princess a chance to steal his blood. When Goku woke up and came to the feast, she and everyone else were all gone. Vegeta figured that his genetic information was stolen.
In Young Jijii's Version, it starts 3 years after the battle with Omega Shenron. Vegeta has obtained the power of Super Saiyan 3. Pan is now 16 years old, as well as the other characters aging less notably. Now, a new villian, named Ize, arrives at earth. He is the Lost Son of Frieza. He reveals his power is over 10x Frieza's (which isn't really THAT impressive)! He starts with fighting Vegeta. Vegeta is cocky and confident, but he loses the battle fast. Vegeta then goes Super Saiyan 4. He easily defeats Ize with the new power. However, Ize reveals his second, far more powerful form. Gohan, like Vegeta, transforms into Super Saiyan 4. But, they still can not win, even with 2 SSJ4s. Goten and Trunks fuse into Gotenks and powers up to Super Saiyan 3. Uub, or Majuub now, joins the battle as well. Now they finally overpower Ize and it seems like they have won. But then, out of nowhere, Ize reveals his third form. Pan tries to help, but is killed. Furious over that, Gohan becomes a Super Saiyan 5 and takes on Ize. After a long fight, Gohan has killed Ize.
Shortly after the last arc, Vegeta and Gohan go to train with the Supreme Kais. Meanwhile, Chyoko and Marble go to earth. However, they are quickly defeated by Gotenks and Majuub. Next, Chyoko and Marble fuse into Chyokomarble. Gotenks transforms to become a Super Saiyan 4. He has the upper hand until the time limit runs out. But, Majuub is strong enough to end the battle, defeating Chyokomarble.
Finally, Vegeta and Gohan are back from training. The heroes now have gathered all 7 Dragon Balls. Their wish is to bring Goku back from the dead. But, the wishes release the Super Shadow Dragons. The heroes fight their respective dragons. Goten wins his fight, as does Trunks, that used the power of Super Saiyan 3 to win his. Uub wins his as well, using Buu's power of anger, but he gets calmed down. Gohan wins his first battle easily. In his second battle he dies, but has to use a suicide attack, which wins him the fight. Vegeta fights in his and wins while only needing Super Saiyan 3. He then fights the last Super Shadow Dragon. He loses, even with the incredible power of Super Saiyan 5. Goku faces him next. He overpowers him at first, the Shadow Dragon uses his next form. Goku is on the losing side, that is until he gets energy from all his friends. He, using Super Saiyan 5, destroys him within mere seconds. Now the Dragon Balls are back and are used to wish all the people who died in the fight back.