This takes place towards the end of Dragon Ball right after the King Piccolo Saga and is heavily based on events that do take place in the anime. In case you don't remember, Krillin, Master Roshi, and Chiaotzu are dead, and that's about all you need to know.
Oolong sat at the coffee table, his fat face resting in his two hands. He watched a purple-haired Launch swaying back and forth in her spot in front of the sink, washing dishes and being her cheery self. He sighed, continuing to watch the beauty work until a distinct, clearcut voice interrupted the calm atmosphere of the Kame House.
"I'm back!" called a three-eyed man after opening the front door, unaccompanied by his usual mime-leech. Oolong crossed his arms and grunted, his snout turned to the air as Tien stood doorway, his hand waving through the air as a greeting. Oolong ignored it, but Tien didn't seem to care. He quickly drifted from the living room to the kitchen, and Oolong finally noticed two grocery bags in each of his arms. He snorted a laugh, seeing the tall fighter running menial chores such as grocery shopping. Even he, the once feared-and-revered Oolong, didn't humble himself to such lowly tasks.
Tien set the bags on the counter, at which time Launch realized he was here. She turned around to him, exclaiming in her merry, ringing voice "Oh, hi, Tien! It's so great to see you!" Her voice was at an even higher pitch than usual, something that Oolong had noticed happening whenever she was around Tien. And then Tien would always blush, the two of them going awkwardly about like this. It was so predictable, it disgusted the pig.
He watched as the once-threatening Tien began removing items from the paper bags, muttering, "It's good to see you, too, Launch."
"How have your bandages been holding up?" she pushed the conversation, flipping her purple hair out of her eyes to turn around and look. He had put a shirt on so as to not scare the grocery store clerks with his wounds, so she couldn't see the majority of the damage.
Setting a can of beans down a little too firmly, he replied, "Oh, they're doing fine."
And with that, their lame conversation ended. Oolong continued to watch, his snout still turned away as if ashamed to even be watching. They continued cleaning and putting groceries away in silence before Tien headed upstairs. Oolong couldn't understand why he was turning himself away from the beautiful Launch, especially when her blond side even liked him. He wanted to do something to help bring the two lovebirds together and end these strange and completely unnecessary meetings.
Oolong the Terrible had an idea.
He stood up from the table and tiptoed to the wall, standing in a position where Launch couldn't see him from the kitchen. He hid behind a vase in the corner, just to be certain he was well hidden from view. Then, looking up the stairs to be sure that the offender wasn't coming back down, he leapt up into the air and poofed, a large cloud enveloping his body for only a few seconds to reveal a perfect replica of Tien. He had him down from the three eyes on his bald head to the funny, purple pants and black shoes he wore around everywhere. Oolong laughed a little, noticing that even his voice had changed as Launch inquired from the kitchen, "Tien?"
"Coming, honey!" he called back, his usual nasally voice having become clearer. It was weird to hear Tien's voice call a term of endearment, but it thoroughly amused the once-pig. So, after entering the kitchen, he placed his hands on Launch's shoulders and said, "How are you doing, buttercup?" Oolong tried suppressing his laughter at the shocked reaction on Launch's face as she turned her head around, almost being one of horror.
Her expression immediately softened, though, as she said, "I'm doing great, Tien!" Oolong saw her face redden as they looked each other directly in the eyes, his third eye being closed. That third eye was giving him a headache, being one too many for the pig to handle; it was best to just keep it shut to avoid letting it wander the room. Other than being a triclops, though, Oolong thought that Tien was definitely an upgrade from his usual piggy self. He felt powerful and in control for the first time in years. He flexed one of his biceps, smirking. Maybe he'd have to start working out, if it would get him somebody as pretty as Launch.
"What's wrong with your eye?" Launch asked curiously, standing on tiptoe to touch the third eyelid curiously.
Oolong turned away and grimaced, saying, "I... I poked it with a stick, sweetheart." Then he placed a palm to his eye, groaning, "It really hurts. I don't know if I'm going to live through this one." Oolong wished that, along with going to Shapeshifting Academy, he had gone to acting school. Fortunately, Launch didn't seem suspicious at all.
"Can I get you some eye ointment?" she asked, having set her sponge down. She began taking her gloves off, setting them down on the edge of the sink as she walked around Oolong, making her way to the living room. Oolong quickly grabbed her shoulders to prevent her from moving any farther; if he risked letting her go through the living room, he risked Tien being at the top of the stairs and the two of them seeing each other. At this point in the plan, that would be bad.
Trying to come up with an excuse to have her stay in the kitchen, he opened his third eye again and pointed to it, exclaiming, "Oh, look! It's all better again, honeybun." At Launch's curious, astonished expression, he pulled her further inside of the kitchen, saying, "Here, let's just stay right in here, okay?"
Launch nodded, baffled by him redirecting her. Oolong was uncertain of what to do at this point to keep the gullible purple-haired Launch from becoming suspicious, so he pulled her closer to himself and said, realizing that his five minutes were quickly passing with this small talk, "Launch, I love you." Before he could even register her reaction, Oolong realized that he could get a little compensation for his services, demanding, "Now kiss me, peaches."
The purple-haired woman stood, her mouth gaping slightly, as Oolong stooped down with his lips puckered. As she began to comply to his request, leaning in towards him, Tien's voice rang from upstairs, "Hey, Yamcha? Are you here?"
The wide-eyed expression Launch had didn't keep Oolong from finishing what they had started, proceeding to give her a big, slobbery kiss. Launch pushed back in disgust after a second, by which time a breeze had picked up through the open window. Oolong immediately dropped her as she began huffing and gasping with her hair tickling her nose, sure signs of bad news.
Finally, she sneezed, allowing snot to fly all over Oolong's face as he noticed her hair immediately turn from innocent purple to threatening blond. Oolong backed away and rubbed his face with his arm, realizing that this could become ugly.
"Tien Shinhan," she barked with a sudden accent, crossing her arms after wiping her mouth, "I think you are the most disgustin' man I've ever met!" She shook her head, pulling the sleeve up on her arm menacingly while continuing, "Didn't your mama ever teach you how to treat a lady? A big, fat, wet one certainly isn't how!"
To add more confusion to the blond Launch's life, a certain three-eyed man entered the kitchen and asked, "Hey, have any of you seen..." His voice trailed as he spotted his doppelganger holding his hands up in defense, and Launch could only look between the two men suspiciously.
"Hey, what's goin' on here?" she asked, standing her ground as her eyes darted from one Tien to the other. Time gave her the answer she was looking for. One of the Tien's ears transformed into pig ones as his nose became a short and snubby snout once again. He lost considerable height and muscle mass, his stomach growing more rotund. His clothes melted away to reveal Oolong's usual outfit of a white shirt with overalls. The final transformation was one that nobody else saw, and that was the pig tail springing from his backside.
Oolong scratched his head as he received a death stare from Launch and a look of awe from Tien. Those looks alone were enough to make him run under their legs and escape through the front door. Launch pulled a machine gun from nowhere, shooting a few rounds through the ceiling while screaming, "You better run while you can, porkers!" Then, turning towards Tien, she said, "I knew that couldn't be you. You look like a man that can actually kiss a girl."
Tien's cheeks reddened at that, still unsure of what exactly happened. Another gust of wind made its round through the house, and Launch sneezed back to her purple-haired self, blinking in bewilderment at the gun in her hand. She dropped it, realizing that Tien was standing so close to her. The two of them jumped back a few steps, continuing their business of blushing, averting eyes, and making small talk.