Rainbow Dash was embarrassed about wetting her pants on the roller coaster, but Fluttershy was able to comfort her - she still loves her even if she wets herself from time to time. (Besides, Fluttershy wets herself more, as Rainbow is well aware)
 
Later Dashie would pee her snow pants while inside a snowman, while wearing these pants underneath. I like to think she wears some kind of boyshort panties underneath those. (Yes there’s no evidence that Rule of Funny didn’t keep her dry in canon but I do like to fantasize)
 
I wanted to do a pee edit for her in those pants after the roller coaster (in part because of my headcanon above that isn’t such a stretch, Rule of Funny aside), and people seemed to like my EqG pee edits of after the wetting. Of course someone else did one for the wetting on the roller coaster.