Rainbow Dash was never into dresses, make-up, or styling her mane, but it's not like she gets mistaken for being male or anything. At least, not until she wakes up in a world where she's the closest thing to a stallion her friends have seen in months.

A bit RGRE? Mostly for comedy, really.

If you haven't heard of RGRE, the story might actually work a little better, but here's a definition anyway since it was requested: RGRE stands for Reverse Gender Role Equestria. Basically, females are the dominant gender. Causes, consequences, etc. vary from story to story.