Is this a sequel to Mothers Don't Need Manuals by ARBPW. As a result it is rated Mature for fetishy material but nothing strong. (Edit: The linked story no longer exists.)

Fluttershy is an adult foal, it's a secret that she's kept from all of her friends except for Twilight. Only Twilight is aware of Fluttershy's fetish or so the pegasus believes.

Naturally when Fluttershy decides she wants to do some more ageplay she goes to see her friend Twilight. But Twilight is too busy to look after Fluttershy.

So Fluttershy is left with only one choice. She'll have to get one of her other friends to join her. But who should she pick, Pinkie Pie, Rarity, Applejack, or Rainbow Dash?