AchieveMe is an addon that will stop the bother when people ask for linked achievements for fights you already know, or make it worse when you try to sneak into an encounter you really don't understand.
That's your own choice. Either way, even for achievements you already have, it's much easier to find them with this as opposed to the default achievement interface. Just type in what you're looking for and AchieveMe will search the names and descriptions of every achievement to find it.
If you have it, you get a link. If you don't, you get two: one for today ("I just got it"), one for a week ago ("I did it last raid lockout".)
You can annoy your friends, annoy people in trade, confuse people, get reported (fruitlessly), or sneak into groups. If people want to be dishonest and link a Malygos achievement, then freak the hell out when they land on a dragon, that's their own problem.
Usage /achieveme or /am opens the window. The rest is self-evident.
005: fixed an error when mousing over an item with an empty search bar
004: initial public release