Trashbin 2
"The only way to win is to not read the crazy, and just fap and/or shlick to the pictures."
-/d/
Meaning
Skub's final form.
SJW stands for "Social Justice Warrior", a particular kind of individual known for attempts to police the internet and the culture of society as a whole by proxy. SJW's usually lean towards offensive attacks such as "doxxing", or hacking and illegally obtaining the personal information of an individual they dislike which is spread throughout the internet in an attempt to humiliate or even financially devastate them.
Generally speaking, the term is thrown around as a buzzword insult towards the liberally-minded or those who are exhibiting more restraint than the user feels is appropriate. In this context, it is interchangeable with the term "Tumblr" as the site is believed by many to be their origin and gathering location (which is actually quite true in many cases, despite the fact the bulk of the site is what one would otherwise expect anything on the internet to be: cats, porn, and memes). While still a major gathering place of devotees, it must be said that Tumblr is by no means the SJW's only enclave. A large number of Internet fora see SJWs in control to a greater or lesser degree, and they appear to have reached critical mass on a site you may have heard of called Reddit.
Origin and Spread
In days long past, the moniker was a positive one, a title self-appointed by the SJWs themselves. "Merry" bands of Social Justice Warriors would roam the land, weeding out regressive scum wherever on Twitter it may be found. This time was short-lived, however, as people quickly realized how ridiculous this was, and began using it pejoratively.
The term was relatively obscure for a time, only seeing major use in /pol/ and other such discussion hubs, with the occasional mention within communities targeted by SJWs. The term entered normie vernacular with the advent of GamerGate, a consumer revolt of gamers, after some journalists accused of corruption called their accusers (and any self-described gamer) sexist.
Behavior
Social Justice Warriors have been noted to show a mob-mentality towards harassing those who they feel (and "feel" really is the right word) have committed wrongs. While anything can draw their attention if it's something they feel makes a person unfairly victimized, like sharks to blood they especially target discrimination based on race, gender, religion, sexuality or political alignment (or anything that they contrive to be this). While they have sometimes addressed legitimate issues such as the aforementioned, as "even a broken clock is right twice a day", they have done more harm than good. There have been highly ironic scenarios where Social Justice Warriors who claim to champion such causes as advancing the position of minorities and women within a field such as comics or the video game industry have in fact attempted to ruin the careers of successful minorities or women within said industries simply for being ignored or for a perceived slight. The irony is lost on them, as in general the confirmation bias is strong and logical or civil discussion impossible. The most extreme form of SJW believe all of society's woes are caused by a poorly defined "patriarchy" or "the Man", somehow keeping everyone who's life has any worth down in a manner similar to medieval superstitions of goblins or devils.
As one would imagine, where there exists Lawful Stupid there will exist Chaotic Stupid as well, usually in the form of the less respectable type of individual who frequent 4chan (in other words, /pol/ and /v/) who intentionally antagonize them, either out of retaliation, belligerence, or simple trolling.
On /tg/
As it pertains to /tg/, SJW represent poor trolling attempts and B8 threads as very few /tg/ products or interests are mainstream enough to warrant scrutiny, or continued interest if they do take issue with it. On other boards their obsessions can be more serious as much conflict (read: complete disaster) can result when particular kinds of Anons and SJW meet. Even if they hate fun, ignoring them and keeping shitty politics out of /tg/ is not letting them win. Just ignore them and have fun.
White Knights
A similar term existed before SJW; "White Knights" are individuals on the internet, generally thought of as male, who are submissive towards members of the opposite sex in all regards to a degree deserving of pity were they not considered obnoxious in their behavior towards anyone else. White Knights are stereotypically kissasses who are quick to push back against any criticism, constructive or otherwise. The term has largely died out except as the verb "white-knighting" in description of SJW behavior when on the defensive.
Recently the original meaning of White Knight now applies to the term "mangina."