Note: Yamcha's canonically 6'0", and I consider Raditz to be 6'6" bare minimum. I also tend to picture saiyans being pretty tactile in regards to intimacy, including lots of facial contact outside of kissing, with brushing noses being a cuter/sillier/less serious form of contact than touching cheeks or foreheads. Just so you know. Yamcha and Raditz are an established couple in this setting.
Two/Three
Yamcha breathed a sigh of relief as he opened the door to his home. It was always good to come back to Kung Pao Rock after an extended absence.
His bedroom was dark when he opened the door, and a familiar ki signature was waiting for him on the bed. The huge figure sat up as he came in, faintly illuminated by the moonlight filtering through the curtains. "Hello, Yamcha."
"Hey, Raditz. I wasn't expecting to see you-" Yamcha's words were cut off as a second ki abruptly unveiled itself from where it had been positioned in the shadows by the door, moving to wraps its arms around him.
"You've been teasing me a lot lately, Yams," Raditz breathed into his ear, tail trailing along Yamcha's leg through his pants, "It's not nice to do that."
"Raditz? What-?" Yamcha's confusion was met with twin chuckles as the figure on the bed slid off it to come and stand in front of him. "How- ?"
"That three-eyed fellow has a few clever techniques, but there was one that especially looked like it had… potential." The Raditz before him purred, tilting Yamcha's chin up so he could kiss him.
"Three-" Yamcha managed to get out before their lips met and he was cut off, moaning a little as the other Raditz trailed kisses down his neck, which in turn allowed the first Raditz to deepen his own kiss.
"Multiform," Yamcha gasped when the need for air finally became greater than the need to keep kissing. "You stole Tien's Multiform technique."
"Mmhmm~" the man in front of him hummed, the other adding, "I like to think I'm doing much better things with it than he ever will." "Much more… enjoyable things…" the first agreed, and Yamcha's breathing hitched as a hand found its way between his legs. "That is, if you're interested," the saiyan behind him murmured.
"And if- I say- no-?" Yamcha panted.
He felt more than saw them exchange a look. "Then we'll reunite and try again as a single entity."
"Not like one of us will be going away wanting."
"But I'd like to try this," the other continued, "I want to surround you, and to saturate you with my scent, so everyone who meets you will know you chose me."
"Kami, you're a smooth talker," Yamcha groaned, leaning back on the man behind him, feeling his arousal.
"Mmm, I'm told I can beg very prettily, too," the Raditz before him leaned down to touch foreheads with him. "So, Yams, what do you want to do?"
The hand between his legs disappeared, and Yamcha did his best not to whimper at its loss. Breathing deeply, willing himself capable of rational thought, Yamcha managed to disentangle himself from the two men and take a step away, looking at them as best he could in the dim light. They watched him, standing not quite side by side, wearing identical expressions of mixed patience and desire.
Coming to a decision, he took a breath and let it out slowly. "I don't know if I'd want to make a habit of this or not, but- okay. Tonight, at least, okay."
Twin smiles glinted in the moonlight, and then they were on either side of him again, the hand back and rubbing him through his clothes, one Raditz nuzzling his neck, the other making quick work of his sash and shirt. Then this one lifted him up with an arm around his hips, supporting him and going in for another kiss while the other divested Yamcha of his boots, then slid the human's pants off, pausing to nuzzle Yamcha's hip as he did so. Then, almost between one breath and the next, Yamcha found himself lying naked on the bed, a Raditz on either side, gazing down at him and clad in nothing but their wild manes of hair.
"Beautiful," one murmured, leaning down to rub his face against Yamcha's, running his fingers through his hair.
"Glorious," the other agreed, apparently content to watch for the moment.
A pair of tails trailed along his inner thighs, making him shiver slightly. "Oh, that's not fair…"
"Why?" the watching Raditz grinned, "I know you like it when I do that."
"Besides, you know I don't play fair," the other purred, moving to trace the shell of Yamcha's ear with his tongue. He stopped with a gasp as Yamcha wriggled and got a hand around the base of his tail, rubbing the area where smooth skin transitioned to fur.
"I don't- play fair- either." Yamcha smirked, then gasped as the other Raditz abruptly joined in, gently disengaging Yamcha's hand from his duplicate and running his free hand down the human's abdomen, producing a shudder.
"None of that now, bandit," he chided, bringing Yamcha's hand up so he could kiss the palm, "I'm in charge tonight. Your job is to… enjoy."
"And to be enjoyed," the other agreed, cupping Yamcha's face with his hand, smiling as the human male leaned into the touch.
"Okay, fine," Yamcha sighed, and let himself go limp, "You're in charge."
He received a pair of rumbling hums that were almost, but not quite, purrs for this, and they both leaned in to nuzzle his neck, one on either side, hands gliding over his body, tails sliding sensuously around his legs and thighs. The two saiyans moved in perfect harmony, murmuring quietly to him, almost a vocal caress, and, oh kami- He threw his head back as a tail flicked over his groin.
"Please, can we go a little faster?" Yamcha panted, face flushed, hips rolling of their own accord, "Please?"
"I don't know, should we make him wait some more?" one gave a slightly wicked grin to the other.
"He got my tail, I'm ready to move to the next bit," the other replied, and Yamcha found himself being deftly maneuvered as one saiyan slid behind him, burying his face in Yamcha's hair, and the other slipped in front of him, bending down for a kiss. Three sets of hips pressed deliciously close together and began to roll back and forth in a mind-blanking rhythm.
For all that he was talkative most times, Raditz tended to be very quiet during the act of sex itself, as though he was focussing too hard on each sensation to have any energy left over to do anything but breathe and keep moving. So it was Yamcha alone who voiced his pleasure as his orgasm hit, covering the soft gasps of his partners. The three collapsed in a tangle of limbs that turned into two as Raditz lost his grip on the technique and became a single being again. They lay there for a moment, panting and purring and curling around each other as if they were trying to become one entity as well.
Eventually, the rosy haze of afterglow lifted enough for Raditz to sit up a little and look down at his lover. "So… enjoy yourself?"
"I wouldn't say no to trying it again sometime," Yamcha reached up to stroke his face. "Is it confusing now? Remembering that from two perspectives at once?"
"You'd think so, but no," Raditz lay beside him again and reached down next to the bed, coming back up with a towel to clean themselves off with. "Definitely not a memory to dwell on in public, though."
Yamcha laughed quietly and snagged the blankets from where they'd been shoved to the end of the bed, pulling them up over the two of them as Raditz tossed the no-longer clean towel back onto the floor. Warm and sated, they fell asleep curled together, content.
I'm honestly not sure if this counts as a threesome or not, since technically only two people were involved. Oh well – hopefully it wasn't too weird… Also, I hereby dub this ship 'Radcha.'