Image imported from derpibooru 
Original Description:
 
Rainbow Dash wet her shorts. Maybe she got a little too excited or maybe she was holding really long and forgot she needed to go. She was a little surprised to feel the warm wetness spreading through her shorts and flowing down her legs. Sunset pokes a bit of lighthearted fun at her and reminds her she wets herself all the time and it feels really good.
 
(Of course the original scenario, where Rainbow kept hitting Sunset in the butt with a paddle, was pretty fun without any need for wettings… though this is the final version of the timeline where she avoids it so in a sense none of the butt smacks count even though she remembers them)