This achievement has changed quite a bit since its release, it got few nerfs, but its still time consuming, however the title is worth the effort.
Criteria for the achievement is:
Honored with Bloodsail Buccaneers
Exalted with Ratchet
Exalted with Booty Bay
Exalted with Gadgetzan
Exalted with Everlook
Exalted with Darkmoon Faire
Exalted with Ravenholdt
So, lets start off with Bloodsail Buccaneers.
Doing this reputation will make you lose reputation with Goblin Factions. This is the only way to get Bloodsail reputation, you will have to grind it back, but more on that later. You will be killing Booty Bay Bruisers, elite mobs located in Booty Bay and also anything else that spawns there. This is best done in a party, you can grind it pretty fast, up to exalted if you'd like, there are no benefits to this apart from having one more faction on exalted, to easier reach 60 Exalted Reputations. You need approximately 2500 kills to honored, and about 4400 kills if you are aiming for exalted.
Don't forget to finish Avast Ye, Admiral! for ''Bloodsail Admiral'' Title also Feat of Strength Achievement.
Steamwheedle Cartel (Goblin Factions)
Now, depending on if you want to keep your hard earned Bloodsail Buccaneers reputation (It's not a must in order to get ''The Insane'' title you just need to reach honored for the criteria then you can lose it) or if you want to abandon it for easier way, you have 2 options.
First Option (Long Grind): Pirates
Easiest way to grind this by far is in the group of 5 in Tanaris behind Caverns of Time on the beach by the ship and on the ship, you need to kill 26330 pirates in order to reach exalted, By being in group, you can cover large area and ''force'' re-spawn the mobs, making the job so much easier. Going with this option, you would keep the reputation with Bloodsail Buccaneers while getting the reputation with Steamweedle Cartel.
When you are done here, you will be exalted with every goblin faction but Gadgetzan (20999/21000), you will have to move to Fray Island, Northern Barrens, southeast of Ratchet to finish the last point of reputation.
If you are farming solo, Venture Co. Evacuee in Grizzly Hills would be much better choice.
Second Option: Cloth
After you finish with killing Goblins in Booty Bay, you can make reputation from Hostile to Neutral with 4 quests (Traitor to the Bloodsail, Making Amends, Mending Old Wounds, War at Sea) however this option will make you lose reputation with Bloodsail Buccaneers with a trade of +500 reputation with certain goblin faction that the quest represents and -500 reputation with Bloodsail Buccaneers.
Cloth needed for this: Linen Cloth, Silk Cloth, Mageweave Cloth and Runecloth. You can buy the cloth on the auction house, rest of the quest items can be bought from vendors.
Darkmoon Faire
Darkmoon Faire comes once a month and lasts for 7 days, you have limited number of reputation you can gain per month, so it will take some time, Only thing you can do to boost your reputation when you are done with monthly quests would be to spend some gold on Darkmoon Cards.
Ravenholdt
This is the hardest reputation to obtain of the ones needed, or well it depends on if you are rich and lazy or hardworking.
There are 2 ways to grind the reputation, one is by killing members of the Syndicate faction, you get 5 reputation per kill and this can take you up to 11999/12000 Honored. Second way is by turning Heavy Junkbox for Junkboxes Needed quest to Winstone Wolfe, you get 75 reputation per 5 Junkboxes.
Now as for how many Junkboxes you need, I will assume everyone has Guild Perk of 10% reputation bonus.
From 11999/12000 Honored to reach Exalted you will need:
with 10% bonus you will need 255 turn-ins / 1275 junkboxes
with 20% bonus (Human Racial or other means) 234 turn-ins / 1170 junkboxes
Easy way:
Hire a rogue. Usually rogues take about 10-15 gold per Junkbox.
Hard way:
Farming Syndicate NPCs should be done in the group, but it can be soloable without losing too much time, you should farm at either Northfold Manor or Stromgarde Keep at Arathi Highlands
Pickpocketing the junkboxes yourself, this becomes problematic if you are not playing a rogue, because you need at least level 70 rogue to pickpocket efficiently. When I did this reputation myself, I heard about many pickpocket spots, but the only one I actually found REALLY good is in the Fields of Honor, Burning Steppes. There are few groups of about 20 humanoids lined up for you to pickpocket them.
If Burning Steppes is farmed by another rogue, I suggest you try Greengill Slave in Isle of Quel'Danas. After you pickpocket them, kill them off, and move on, respawn is about one minute, and you will have small downtime while moving from one spawn location to another
Legendary Quest
Rogues can do the legendary quest for the Fangs of the Father starting from Proving You Worth which will give them total of 3150 upon completing the quest line, reducing the number of Heavy Junkboxes needed, this should be done after obtaining at least 11999/12000 Honored reputation with Ravenholdt.
Some Helpful Tips
Guild:
While doing this, be sure that you are in at least level 12 guild for Mr. Popularity Perk.
Your guild also needs to have A Daily Routine achievement for Battle Standard of Coordination and you need friendly reputation with your guild to buy it.
Events:
Be on the lookout for events.
Darkmoon Faire - Darkmoon Top Hat 10% reputation buff you can buy it for 10 Darkmoon Prize Tickets or get it from Darkmoon Game Prize which is a reward from one of the Darkmoon daily quests
Hallow's End - Unburdened 10% reputation buff that lasts for two hours, Alliance players can get it by visiting the Wickerman outside the Stormwind, for Horde players its located in the Ruins of Lordaeron in Undercity.
Pilgrim's Bounty - The Spirit of Sharing 10% reputation buff that lasts 1 hour. You get this buff after getting five stacks of each food at a bountiful table. You can find a Bountiful Tables in every town with an innkeeper.
Rogue:
Macro:
#showtooltip Pick Pocket
/console autoLootDefault 1
/cast [@mouseover, exists] Pick Pocket; Pick Pocket
Achievement in Chat
/script DEFAULT_CHAT_FRAME:AddMessage("\124cffffff00\124Hachievement:2336:"..UnitGUID("player")..":0:0:0:0:0:0:0:0\124h[Insane in the Membrane]\124h\124r");
/console autoLootDefault 1
/cast [@mouseover, exists] Pick Pocket; Pick Pocket
Achievement in Chat
Mailbox:
Engineering can save you so much time with Ravenholdt, MOLL-E is a life saver.
If you are not Engineer you can use Argent Squire if you bought Argent Pony Bridle.