The same thing everyone else is spoiler boxing:

Solid Episode! Had a big stupid grin on face the entire time. The test at the end was a bit odd when they could have just quizzed the Pinkies about her life rather than 'if you get distracted Twilight will send you to the cornfield the pond' but I'm not gonna complain

Another episode, another mysterious book that they spend just enough time on to make it seem like foreshadowing.

Also, Granny Pie knew about a secret cloning pond even Twilight had never heard of, and she taught Pinkie 'Giggle at the Ghosties.' Was Pinkie's grandmother some sort of badass adventurer in her day?