Since some ppl are having difficulty with this ill help explain it. Here is how the code is broken down:
Code:
/script ChatFrame1:AddMessage("\124cffffff00\124Hachievement:2186:0000000000F437F3:1:3:8:9:4294967295:4294967295:4294967295:4294967295\124h[Scarab Lord]\124h\124r")
is

However, if you still dont understand and just want to have fun you can use these commands (you can make 3 macro's if you like and just click them at the start)
Run these 3 scripts:
Code:
/script function a(X) m=date("%m"); d=date("%d"); y=date("%y");p=UnitGUID("PLAYER");if X == nil then x=math.random(10000); else x=X;end;I,N=GetAchievementInfo(x);if N~=nil then b(p,x,N,m,d,y); else a();end; end
Code:
/script function b(p,x,N,m,d,y) M="\124cffffff00\124Hachievement:"..x..":"..strsub(p,3)..":1:"..m..":"..d..":"..y..":4294967295:4294967295:4294967295:4294967295\124h["..N.."]\124h\124r" ChatFrame1:AddMessage(M.." ID# "..x); end; a();
Code:
/script function c(T) if T==1 then Ty="GUILD"; else Ty="EMOTE" end; SendChatMessage("has earned the achievement "..M.."!",Ty); end;
after running these 3 scripts once (you dont need to run them after this) use the following commands:
/script a() <--generates a random achievement
/script a() <-- generates the achievement relating to the achievement ID
e.g. /script a(610) is [Death to the warchief]
/script c() <-- Displays the emote " has earned the achievement "
e.g. doing /script a(610) then doing /script c() will result in " has earned the achievement [Death to the warchief]"
/script c(1) <-- does the same as above but in guild (note: you will still have the : after your name)
proof: (im horde)


EDIT: If you make these into a macro you can just click the middle macro to generate a random achivement
NOTE: The achivements generated will always have the current date and be for that character. it is possible to make achievements with any date in the future or past too and possible to make achivements for other people by changing the id to theirs, their id can be obtained using /script ChatFrame1:AddMessage(UnitGUID("TARGET"))
NOTE2: To get the achievement ID got to www.wowhead.com and find the achievement (e.g. Death to the Warchief!) the URL at the top will contain the ID (e.g. for Death to the Warchief! it will be wowhead.com/?achievement=610 so 610 is the ID)
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For those of you interested here is a complete breakdown from http://www.wowwiki.com/AchievementLink
Code:
|cffffff00|Hachievement:2186:00000000002FDDE9:1:12:19:8:4294967295:4294967295:4294967295:4294967295|h[The Immortal]|h|r
* "|cffffff00" - Colorizes the link (see itemLink)
* "|H" - Hyperlink introduction
* "achievement:2186" - Achievement ID
* "00000000002FDDE9" - Character ID
* "1" - Status of this achievement. "1" means finished, and vice versa.
* "12" - Month this was finished.
* "19" - Day this was finished.
* "8" - Year this was finished, starts from 2000.
* "4294967295" - Flags of details of this. (#1)
* "4294967295" - Flags of details of this. (#2)
* "4294967295" - Flags of details of this. (#3)
* "4294967295" - Flags of details of this. (#4)
* "|h" - Hyperlink data concluded, text follows
* "[The Immortal]" - Display text
* "|h" - Hyperlink conclusion
* "|r" - Returns color to normal
(4294967295 is the highest number you can get using 32 bits)