ssj 

"Super Saiyajin" from the anime Dragon Ball Z

the above is the original, japanese, name of the race in the show. After it came to the US and rest of the world, the racename was changed to: "Super Saiyan".
SSJ is therefor a reference to the original "Super Saiyajins".

It is used to describe different forms of the heroes of the show.

Goku is SSJ2, the second level of SSJ.

ssj by Nivyan December 23, 2007

ssj 

super saiya-jin, an advanced level of power reachable only by members of the saiya-jin race or saiya-jin/human hybrids. it causes the person's hair to turn gold and stick up, the person's eyes to turn turquoise, and increases the person's fighting strength several times. it is usually the result of extreme anger. from dbz.

goku was the first to become a ssj.

ssj by d-shadow January 16, 2004

SSJ 

acronym for the term "spreadsheet jockey". Term used for an investor who judges the relative worth or attractiveness of an investment in a company (usually a startup) based solely on a spreadsheet model of financial metrics.

Don't take that guy's money, he's a SSJ and will drive your company into the ground.

SSJ by Sanjay_Parekh October 6, 2008

SSJ 

Super Saiyan

Damn good person on the boards

SSJ is awesome.

SSJ by SSJ September 25, 2003

SSJ 

Super Sad Jew

Derogative term for a Jew. Often used as slang for a Jew who lost family during the Holocaust.

His grandma was killed in the Holocaust, and now he's bitching about it, what an SSJ.

SSJ by FlippyBaetender October 20, 2018

ssj 

a big hairy man gimp

A half man half yeti combo

ssj by Adz innit February 4, 2003

ssj 

ssj is a new kind of eliteness, how he is so elite, it is unknown, but truly, he is as elite as a old man crossing oveer the road.

ssj headshot everyone

ssj by ssj February 4, 2003