Insane in the Membrane

Insane in the Membrane is a Feat of Strength that rewards the title. This feat requires you to become honored with the Bloodsail Buccaneers and exalted with the Steamwheedle Cartel (Booty Bay, Everlook, Gadgetzan, Ratchet), Ravenholdt, and Darkmoon Faire. It does not require that all of these reputation levels be reached at the same time. Raising reputation with these factions is typically very difficult, time-consuming, and costly—hence the title.

Bloodsail Buccaneers
Reputation with Bloodsail Buccaneers is gained by killing NPCs belonging to the Booty Bay faction. For a detailed list, see Bloodsail Buccaneers reputation guide.

When you reach or higher with Bloodsail Buccaneers, visit Fleet Master Firallon in his ship off the south-east coast of Stranglethorn Vale and complete Avast Ye, Admiral! for the  title.

Steamwheedle Cartel
Steamwheedle Cartel reputation should be earned after Bloodsail Buccaneers, as you will ruin your standing with one by attacking the other, and it better ends up on the goblins' good side.

You can kill non-Bloodsail pirates or Venture Co. NPCs throughout the world. Each pirate or Venture Co. NPC grants full reputation for the "local" Steamwheedle faction to the end of and 50% reputation to the other three factions through to. Everlook has no local faction that grants reputation, but reputation with Everlook will improve as NPCs are killed to increase reputation with the other three cities.

Ravenholdt
The Ravenholdt grind begins with killing Syndicate NPCs. They can be found in Arathi Highlands, in Stromgarde Keep and Northfold Manor. Each Syndicate member gives 5 Ravenholdt reputation, to the end of.

Afterwards, you must to turn in 5 x to Ravenholdt Manor, for 75 reputation. These junkboxes are attained by rogues via the Pick Pocket skill from level 55+ mobs. If you do not have or want to level a rogue, you may be able to buy the junkboxes or hire a rogue to farm them for you. Lootable containers cannot be auctioned, but the boxes can be traded and/or mailed.

If you do have a rogue, the most popular location for farming is Lower Blackrock Spire, as any of the orcs and ogres inside can carry the junkboxes. See Farming Heavy Junkboxes for more info.

If you find you're being caught too often, additional points in Subtlety may help, specifically Master of Deception, Camouflage (rogue talent) and Preparation.

Darkmoon Faire
Darkmoon Faire reputation can be gained by playing sideshow games, doing profession quests, and turning in Darkmoon Cards. Since its redesign that rolled out in patch 4.3.0, it is no longer challenging or tedious to gain reputation with this faction.

History
Back in 2009, Ancilorn stated that this achievement would not be removed from the game with Cataclysm, and that "you don't have to rush to have this done before the expansion." At BlizzCon 2010, however, Greg Street was asked if it will still be possible to get the achievement, to which he responded: "The biggest problem are the changes to the bloodsail buccaneers, that kinda put a bullet in that feat of strength for now. It's fun to do painful things in WoW. If there's a huge outcry for it we'll try to put something equally brute in the game." Days later Bashiok indicated on the forums that it will be impossible for most people to complete this Feat of Strength after Cataclysm.

However, Beta Build 13277 removed Shen'dralar from the criteria, and then a short time later, a blog post on the WoW Community website confirmed changes which will allow the achievement to still be obtainable after The Shattering:

Trivia
This achievement is a reference to the Cypress Hill song of the same name.