Humanized Luna x Celestia. Luna's just gotten back from the moon. She hasn't seen her sister in 1,000 years. Damn is she horny.
Twilight Sparkle has been a little down. Her friends have left Ponyville one by one on important errands. When a sudden invitation arrives from Pinkie Pie, informing her of a surprise party with all her friends, she's so excited by the idea she can't sleep! Celestia's cleverest student sets out early for Sugarcube Corner unaware that the 'surprise' waiting for her may not be entirely to her liking.
One night I had a disturbing idea, why not make a story where Pinkie goes inside Rainbow?
So, with the help with my extremly messed up mind I thought out this story.
It's pretty much rough with a few typo's because I typed this in note pad, and the fact that half of it contains whatever I thought of as I was typing doesn't help.
I could have spent more effort on a less comedic ending though