Blue Response

The NPC for this achievement is a recolored [npc=69128], and can be found in the South West of the Isle of Thunder.
When the Hatchling Skyscreamers are feared by people coming close to them, they can respawn as a blue version.
The blue Hatchling Skyscreamer has the same name as the other Skyscreamers, but has a unique NPC ID

/npcscan add 70215 Hatchling Skyscreamer
(for NPCscan)

Unfortunatly the wow API will only let you target by name, not by unit ID, so while this will alert you to it's presence, finding it will still be up to you.

It should be noted that you simply need to get close to the blue hatchling for it to be "feared" away, and you will get the achievement. You don't need to emote /shoo or anything.

This is probably one of the most clever names for an achievement ever. It's called Blue Response, and you have to scare away the rare "blue" hatchling after it appears. What this is referencing is on the actual WoW forums how people are constantly asking for the uncommon ("rare") response or post from a forum admin, who is referred to as a "Blue". The funny part about this is that a lot of the time after a thread receives a blue response, people usually complain, argue, and even sometimes shoo away the blue for almost no reason, which is actually the exact requirements for this achievement, to successfully scare away said "Blue" Skyscreamer Hatchling. XD