Disclaimer: I do not own anything related to Doctor Who. I don't even own a rainbow, although I think that would be pretty awesome.

A/N: Sorry for the wait on my WIP 'Universal Conqueror', but I was in the hospital for a week due to medical issues and so was unable to work on it. Then I got in a slump and decided to take a break and post this instead. But to those of you who are waiting for an update, it will come soon.

A/N 2: A special thanks to Bas_math_girl for answering my question pertaining to the existence of Skittles in Britain.

"But Donna, I'm serious!" the Doctor all but whined to his companion.

"How thick do you think I am? Do you really expect me to believe that?" exclaimed a very aggravated Donna. "Next you'll be telling me that leprechauns actually exist. I've never claimed to be the smartest person on earth, but I'm not an idiot."

The Doctor's face bore the indignant look that he wore so well whenever someone doubted his word, as if the very notion of him being wrong was inconceivable.

"I'll prove it, and I reserve the right to say 'I told you so' when I do."

"Fine, but no cheating. It can't be on another planet. Otherwise it doesn't count."

He looked downright insulted, "Do you really think that I would actually cheat to prove my point?"

"I'm not even going to dignify that question with a response, Spaceman." She crossed her arms and gave him a look that just dared him to contradict her.

He didn't get the chance, not that he would have anyway, because at that very moment, the TARDIS landed with a heavy thud. Wasting no time, the Doctor raced to the doors and flung them open. Donna quickly came up behind him and they both made their way out of the TARDIS to see where exactly they had landed.

The immediate view was breathtaking. They were facing a decent sized lake that was fed by a waterfall to their left. The cliff from where the waterfall was extended all the way around the area they were in, creating a large circle. It was completely closed off from the rest of the world, inaccessible except by falling off the cliff. The diameter was a good mile across. The rest of the enclosure was filled with all sorts of vegetation, both trees and plants, in some of the most vibrant colors Donna had ever seen.

The lake itself was not to be ignored. The thirty foot waterfall cascaded down into the waiting pool of cerulean water. It was not as large as some lakes Donna had seen, but it was big enough to swim around comfortably in without feeling cramped. Coming out of the waterfall was the object of their journey: a rainbow.

It had started earlier that day when Donna had been eating a packet of Skittles candies and reading a magazine on the jumpseat while the Doctor fiddled with some wires under the console.

"You know where those came from, right?" He asked, nodding to the candy in her hand.

"The candy company." Donna replied lazily.

"Yes, but I mean, do you know where they got the idea from?"

"Never thought about it really. I don't exactly spend my day wondering where the ideas for different candies come from."

"Look at the slogan."

She looked down at the packet in her hands. "Taste the rainbow. " She stared at it for a minute before realization dawned.

"Oh, you are kidding me! Seriously? I don't believe it."

"Why not? After all you've seen is it really that hard to believe?"

She thought about it. It really wasn't. After talking potatoes and flying fat, it really wasn't that much of a stretch to believe something like this. But really, a rainbow having a taste? The same rainbows that she spent most of her childhood believing held a pot of gold at the end of them. The thought of it was fascinating.

But she couldn't just let him think that she'd believe anything he said. Otherwise, there would be no telling what idiotic nonsense he'd come up with. No, he was going to have to prove this one.

Keeping her face composed, she looked up from her packet of Skittles and looked straight at the Doctor, "I don't believe you."

And thus had begun the whining of the Time Lord about how he was in fact telling the truth, while she continued to demand that he show her proof.

And so here they were.

The Doctor raced headfirst into the water, heedless of any creatures that may be living beneath its surface. When he finally reached his destination, he began to tread water and turned to his companion.

"Come on, Donna. The water's great." He was smiling at her with that big, adorable, goofy grin of his that he wore whenever he was overly excited about something that most would find mundane.

"What, just like this? With all my clothes on?"

"I'm wearing mine. But you could always take them off if you wanted. I'd have no objections." He shot her a cheeky wink.

"Oi! I'm going to slap you in a minute."

"You have to reach me first, and at the rate you're going, that may take a while."

She was still hesitant, "But I like this outfit. I don't want to ruin it."

"Ruin it? Donna, it's water, not engine oil. Come on, live a little. That's why you decided to travel with me isn't it?"

"I suppose."

"Then come on."

Sighing, she stripped off her brown leather jacket -because no way was she letting that get wet- and waded into the water, which was cold, but not unpleasantly so. When there was no land to walk on any longer, she swam over to where the Doctor was waiting by the rainbow.

"You're gonna love this, Donna. This is brilliant. You just pick a color, stick your tongue out, and lick. Like this." He poked his tongue out and proceeded to lick the red strip at the top of the rainbow.

"Mmmm, strawberry. Go on, try it."

"Do I have to stick my tongue out like that? Can't I just swipe my hand through it and taste it like that?" she asked as she made a gesture of demonstration in the air.

He looked a bit disappointed. "Well, I guess you could; but it's more fun my way."

"I'm not doing that. I'd look like a complete idiot."

"Are you saying that I look like an idiot?" he asked, slightly affronted.

She said nothing, but rather fixed him with a knowing look.

"Come on Donna. Please." He looked quite pitiful, especially with the way his hair was hanging down in his face, and she felt her resolve crumbling.

"Alright, fine, but no laughing."

"I would never." He exclaimed in a tone that meant he most definitely would.

She tentatively stuck out the tip of her tongue and ran it along the green strip of the rainbow. Her taste buds were bombarded with the explosive flavor of lime. She scrunched up her face in mild disgust.

"Ugh, it's sour."

"Try the grape instead. It's a bit sweeter."

She tried it and discovered that yes, the violet was much more pleasant. She ran her tongue along it again, savoring the taste. It tasted of actual grapes, and not the artificial flavors that were used in the candy, which, in Donna's opinion, made it taste even better than she had expected.

They spent the next few minutes trying out the different flavors. The blue of the rainbow tasted of blueberries and Donna asked him why they had not included that flavor in the packets. He thought about it before informing her that he really didn't know.

"Wow, you mean there is something that the great and mighty Time Lord doesn't know. I'm shocked."

"Yeah, but still…."

"What?"

He was grinning like a Cheshire cat. "I told you so."

She couldn't help but smile in return, "Yeah, you did Spaceman." She reached over and embraced him in a hug.

"This is great. Thank you Doctor."

"Glad you like it."

After spending a couple more hours in the secluded area, they made their way back into the TARDIS.

"Well Doctor, I have to say, I'm impressed."

"Really? Well, I'll have to write that one down in the record books."

"You better, because it isn't likely to happen again." No need to tell him that nearly everything he did impressed her. His ego was big enough already.

"Oh, we'll see about that. Donna, have you ever had a Starburst…"

THE END