One day while skiing, Rainbow Dash tells Sunset Shimmer that she often wets her snowpants for convenience. Sunset is curious and decides to try it out.

Contains: Wetting. And brief mention of messing.

This might seem another ludicrous scenario but I have heard some people say on forums that they do actually do this, so it is a thing, and let's face it, Rainbow Dash is one of the two most likely (other being Pinkie Pie).

One more note is, I thought of putting Sunset in her Sunset's Backstage Pass pants under her snowpants instead of jeans. If you would prefer that, let me know and I will change it, though I might be planning a Sunset/Twilight story where she wets that outfit (but it will have more than just wetting).