Pinkie Pie loves everything fun and exciting, like the parties she throws left and right. Yet, she had hidden a secret side of herself away, in the Dungeon she managed to establish, right under the Muzzles of everyone in Anthroville. In part because she kept the Dungeon strictly on an Invitees only basis.
Pinkie Pie has her own ideas, her own brand of most anything she finds handy or use-full, just like the Helicopter and the Megaphone.
Some of her friends may know of her abilities, like the Partycannon, the Balloon off of the Flank trick and numerous others, up to the point of where she breaches what was known as the fourth wall. Thus enabling her to go places unseen, in a very short time.
Pinkie Pie has a driving need to see everyone Happy. At least everyone in Anthroville, but why stop there, if you can make just one more happy smile and a few more laughs? With that, she had to go out and see each and every place, and make each and every inhabitant smile and laugh. What would possible go wrong?