Author's Notes:

This chapter is based off her appearance at the end of the second segment of Holidays Unwrapped. Canonically she probably stayed dry, between Rule of Funny and fiction physics (like the Main 6 being locked up by Starlight for days, evidently without needing to pee due to lack of desperation or puddles), as this is a throwaway joke they barely go into any detail on, but I do like to fantasize about a more realistic approach.

Rainbow Dash was hiding inside a snowman. The snowball fight was only two days away, but no one would be suspicious of a snowman that was there for so long, making it the perfect opportunity for a sneak attack. She had told her friends that she was going out of town for a while and would be back in time for the snowball fight. She had eaten some energy bars and drank a lot of energy drinks, so she wouldn't get tired or run out of energy, and her winter outfit was keeping her relatively warm, even her head for some reason. It was still cold, but not overly so.

But there was one thing she hadn't counted on. She had to pee. Only an hour in due to all the energy drinks she had drank. She considered running for the bathroom, but she really wanted to ambush someone. It was too good an opportunity to miss, and she was already here, inside this snowman that no one would suspect had her inside it. She decided to hold it. She'd never heard of anyone holding for two days, but she was Rainbow Dash. If anyone could do it, she could.

Five hours later, Rainbow really needed to go. She fidgeted a bit where she was, feeling waves of pee sloshing inside her. This was getting pretty bad. What could she do?

There were three options. The first was to just give up the whole plan, go inside, and get her relief. She considered it, but decided against it. She couldn't wait to see the look on her victim's face after she surprised them with a snowball.

The second option was to try to hold it. Not likely. If it got this bad after five hours, there was very little chance she would make it to the snowball fight, and even if she did, her desperation might make her aim go off.

The third was to just let go and pee right here. Not something she'd normally do, but she had a feeling she'd end wet anyway.

However, returning to her second option, she thought, it might be a good opportunity to see how long she could hold it, so she'd know how close she was to wetting herself on other occasions, like a really long soccer game on a hot day where she had to drink a lot of water. There were times she thought she wouldn't make it but she did.

Her heart was racing as she held her very full bladder. She had to pee really badly, and she was sure she wouldn't last the first day, but there was no doubt in her mind that all that pee would end up in her pants. She was about to wet herself, and she wasn't going to do a thing about it other than hold as long as she could.

She held herself and fidgeted slightly, trying not to fidget so hard that it made her snowman fall apart.

Quite impressively, she held it another half hour, during which she reached levels of desperation she had never known before. She now realized she hadn't been anywhere near wetting herself at those games. She was sure she had a stronger bladder than most people, she had seen Fleur wet her shorts at the festival at the back of the Bathroom Line.

Then she leaked a bit into her skintight black pants that she wore under her snowpants. She whimpered, thinking this was the wetting, but no more came out for the time being. So, it seemed leaks like these came before the wetting.

As the minutes went by, Rainbow leaked a few more times, slowly turning her pants from damp to wet, and wetting the inside of her snow pants slightly. Her skintight gray boyshort panties were soaked. She couldn't believe this was happening, let alone of her own accord. She'd try to keep this as quiet as possible, but decided she would tell Fluttershy. The poor girl wet herself so much, she'd definitely feel better about it knowing her girlfriend had wet herself at least once. It might even bring them closer.

18 minutes after her first leak, Rainbow couldn't hold it anymore, and the floodgates opened. There came a stream she could not stop, and before she knew it, she was peeing full force. She could hear the sound of her stream passing through her skintight pants and spraying her snow pants, and felt exceptionally foolish. She, Rainbow Dash, a world class athlete, was peeing herself. In a situation she put herself in and could have left at any time, no less. But the warmth did feel nice, and it would be worth it in the end.

Her snow pants absorbed most of the damage. She wasn't sure whether the wetness would show when she got out of her snowman, but they definitely felt very warm and very wet inside, and she could easily notice a pee smell.

Well, this was it. There was no turning back. She wet her snow pants, so she might as well make it count.

As the hours went by, Rainbow became bored, waiting inside the snowman in her wet pants. But she was able to entertain herself by thinking about Daring Do movies, or playing sports, or else just planning her surprise attack. She couldn't wait for that. She peed again before the second day, this time voluntarily, for her holding muscles were tired, and there was still a lot to go through her after her first wetting.

Finally, the day of the snowball fight came. Rainbow waited eagerly for her unsuspecting victim. It had all come down to this. Aside from the state of her pants, she smelled a little due to having not washed the entire time.

Eventually, Pinkie Pie and Rarity came in front of her. Rainbow seized her opportunity to do what she had waited this long for.

"Haha! Sneak attack! Bet you weren't expecting this!"

Rainbow Dash threw some snowballs at Rarity, who casually blocked with her barrier.

"Aw, no fair! I spent two days as a snowman for that!" Rainbow thought, maybe she shouldn't have loudly announced her sneak attack and given Rarity time to react. A snowball hit her, knocking her on her back. As Rarity and Pinkie Pie laughed, Rainbow lay with her eyes closed, disappointed that she had wet her pants for nothing.