Luna, strangely enough, receives a letter from Princess Twilight Sparkle. From the letter she can discern two things. One, Twilight definitely has a drinking problem. Two, she really loves her. And a third can go to being extremely kinky.
People like Button's mom. Some really, really like her. So it's no surprise a few fanart and stories are made in her favor. And now poor Button has to deal with the end result for some inexplainable reason.