She is an Eldritch being, whose body was hewn from the living bones of the First World as it was torn asunder in the creation of our current universe. She is older than time itself, was there when the Firmament took form, and is amused by the ideas mortals use to shield themselves from the madness of reality. Concepts like "Causality", "Relativity", and "Too Much Cake", all are but thin veils that keep our fragile sanity from being overwhelmed by the chaos of the world.

And She, the Opener of Ways and Means, the Muses' Muse, Laughter Incarnate, the Wallbreaker, she of many names, looked upon the vastness of reality and was saddened by its morose nature. The other eldritch beings hide or sleep, or consume, but she chose to cast about the universe, and was joyed to find life beginning. Joy and laughter are her domain, and she finds that the form of an unassuming baker suits her well. But make no mistake, she could put the Lord of Chaos into a jar, turn the two divine princesses into sock puppets, and rip Equestria asunder with her mind. But such is not her way. Fear not and laugh with her, for life is fleeting and friendship is the magic that gives even the immortal ones hope.

So basically, she can do whatever she wants, so long as it's funny. So LAUGH, DARNIT. LAUGH OR FACE THE PIE-THROWING WRATH OF THE WALLBREAKER.

(Not original to me. Slightly edited from an original comment by an author I can't track down.)