Well, that happened.

It was a normal day for Rainbow Dash.  Causing the weather to be terrible (or nice depends on the day), coming up with new stunts, and lounging around.  She was in the midst of practicing a new stunt when she stops her upwards momentum and starts plummeting down to the ground.  As she was attempting to flap her wings in order to land safely a sudden flash of cyan light flashed and she found herself in front of Sugarcube Corner.  As one would think she was confused, mainly because she had been flying over Sweet Apple Acres which is on the other side of town.  She thought that most likely her stomach got the better of her and she decided to go over to Sugarcube Corner and didn't realize it.  She decided to go inside, it was her favorite time to eat there (when Pinkie is working the counter and it's only them two there.)

When she got in she realized the place was much messier than usual.  She decided to ring the bell that Pinkie hid in case of there-is-nopony-at-the-counter emergencies.  Not long after Pinkie came tumbling down the steps and appeared behind the counter.

"Hiya Dashie, What ca.......," Pinkie said suddenly stopping at staring at Dashie's forehead.

Rainbow was doing the same thing to pinkie only thing being that she was staring at the sides of Pinkie's body.  Rainbow Dash ended up breaking the silence.  "Why are you staring at me Pinkie?"

Pinkie reached into her mane to pull out one of her mirror emergency mirrors. (Before you ask an example of a mirror emergency would be something like Rarity forgetting hers)  Before Rainbow could ask why Pinkie had that mirror in her mane she was struck with an image of a cyan unicorn with magenta eyes and a rainbow mane.

At first she laughed and said that it was either a dream or a prank.  Pinkie had assured her it was neither of those.  Rainbow then looked at her wings, they were gone.  At first she freaked out about them being gone, and then she realized that her being a unicorn explained why she all of a sudden appeared in front of Sugarcube Corner.  Lastly, she decided to turn the open sign so it said that the place was closed and decided to take Pinkie upstairs and show her why she was being stared at.

Pinkie didn't really know what to think.  She was feeling almost every emotion at once.  Then, she started the questions.  After a couple minutes of "how did this happen," and, "can you believe," Rainbow Dash decided that the only way to do anything else was to put her hoof in Pinkie's mouth.  Pinkie promptly shut up.

Rainbow Dash basically said that they needed to find the rest of the mane six to see if the also got mixed up.  She finally said that she would get Twilight and AJ whilst Pinkie got Rarity and Fluttershy and to meet up back at Sugarcube Corner.