Raymond Dallas, a short, senior college student, gets caught in a dare with his two roommates, which he lost, making him take yoga class dressed as a girl with a rainbow wig, a pair of cyan blue wings sown to the back of the shirt, and a rainbow tail sown to the rear. He was embarrassed that he was taking that class, but things went so wrong during the class, he actually changed genders, name changed to Rainbow Dash, and nobody around him seemed to notice. Not only that, but his entire life was being rewritten, and he was the only one to know about it. And it turns out that the woman next to him during that class became his/her mother, and de-aging him back to Junior Year in High School.
Then when "she" arrived back at the apartment he stayed at, it turns out that he still lived there, but with "her" family and foster sister living there instead of his two roommates for college. "She" was trying to figure out what was going on while the reality around her was slowly changing around her. Especially when her own body was changing to one that's not human, but an anthro pony, but still aging like a normal human. Will Raymond/Rainbow find out what's going on with the help of "Rainbow's" six best friends; Twilight Sparkle, Applejack, Rarity, Pinkie Pie, Fluttershy and Sunset Shimmer, which they had an answer that "she" was not expecting.