Party Pie

And here's Pinkie! I also can't explain why this outfit is my favorite, I just love it. The can-can dancer one was a big competitor. The "present box" one is also great. But I kept going back to this one.

Now only Twily remains~

Done in Illustrator CS2.

Other outfit series:

Applejack: Gala Apple
Fluttershy: FlutterDress
Rainbow Dash: Armor Dash
Rarity: Frenchity
Twilight Sparkle: Twily Gown