S04:E12 - Pinkie Pride

Title: Pinkie Pride
Air Date: February 1st, 2014
Synopsis: An elated Pinkie Pie is planning the biggest and best “birth-iversary” party ever for Rainbow Dash, but when another party planning pony named Cheese Sandwich rides into town, plans change. Soon, everypony is so excited about Cheese Sandwich’s party that they forget about Pinkie Pie, but her pride won’t let her go down without an official “goof off."
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OMG!!!! This episode was a complete BLAST, they even had freaking Wierd Al on the show! XD

And it also looks like another one of the mane 6 got their key also!