Shinju alternatively means the art of hotness or having a extremely big/huge/gigantic penis.
Also related is SHINJUWAZKAKEAZAZAZAZALALALA!
Which you shout out when you're having a good time. Example: Doing the bang bang.
Guy: Hey baby, wanna Shinju tonight?
Chick: HELL YEA!!!
Guy: Take a look at my Shinju
Chick: THATS HUGE!