Ninjas weren’t known for stealing stuff, they were known for spying on people and assassinating them. But stealing stuff is literally all pirates did, there’s even a word for it “piracy”.
So why did the WoW community coin the term “ninja looting” instead of “pirate looting” or even “piracy”?
Ninja looting this thread. It is now a fox looting thread. 
Why not both?
Hrm… This is acceptable.
Because they assassinate all hopes of you getting that Thunderfury binding
What are you talking about? Ninjas stole all kinds of stuff.
Source: Definitely not a pirate
It should have been called ‘Viking’ looting.
Ninjas and Pirates are overrated.
Some players would be extra sneaky about it and throw in a last second “need” on a piece of gear and bam, you just got ninja’d.
My personal guess is that the ninja infiltrates you own group/raid. A pirate is more open about their intentions making them more honest.
The WoW community didn’t coin the term, they just took it from MMOs before it. The term “Ninja Looting” was from MMOs prior to WoW that did not have participant loot locking on mobs. A common scenario would be a ranged class would kill a mob and before they could walk over to loot it a stealth class, like a rogue or ninja, would appear and loot the creature before the actual person who killed it could loot it.
Since there was no mob tagging anyone could loot a kill and run off with all the contents. Classes that did this constantly were rogue and ninjas, hence the name “Ninja Looting”.
When it came to WoW the game has always had mob tagging, so only the person who tagged the mob would be able to loot it, hence solving the issue with ninja looting. The problem though is that the term became overused in situations where people didn’t get loot when they felt they should have, either someone rolled need on an item because the game allowed them to roll, or they joined a group with Master Looter rules and got upset when the loot master took the loot they were allowed to take by being the master.
Ninja Looting, by its definition, has never happened in game (without a bug occurrence as explained later) because of tagging and loot settings. The only known case I can remember happened due to a bug where a legendary necklace that wasn’t supposed to be in the game dropped off a boss in MC and it was looted by someone that didn’t have the rights to loot it since they were not the master looter.
That necklace was quickly removed from the game it and it never showed up again.
Edit: I was wrong about the necklace being ninja looted. It was able to be master looted as normal.
Here is article about the item. It also has a link to the story about the time during Wrath when a GM accidentally left a legendary chest piece, that with a single click could kill everything in a radius, on a player’s character.
The ninja looters were disguised as ordinary party members.
odin is with us
Because pirates take things by force.
Because there’s not enough booty.
I can’t help it i’m like if a frog stood upright
Did someone say…