Princess Celestia employs the Elements of Harmony to test the latest advancement in Equestrian bedroom manufactuing, also known as The Orgasmatron.

After hearing about Twilight and Rarity's "grand time" on Earth, Celestia decides that she wants to see what was so great about it. She grabs Luna for the ride, and sets out for the home of a specific human. What human? YOU, of course

Twilight Sparkle pleasures herself with a mare-sized checklist. I'm fairly certain that that concept speaks for itself.

Imagine having 2 incredibly aroused anthropomorphic ponies in french maid outfits constantly trying to seduce you. Now, imagine hating the thought of having relations with an anthropomorphic pony, and you have tonight's tale.

She can break it, but she can't break through it.