What Does OSS Mean? BJJ's Most Popular phrase explained.

Have you heard someone at your gym say "OSS"? It gets thrown around almost like a Jiu-Jitsu meme. But OSS has a deep history outside of BJJ. It is a word of many meanings in Judo, Karate and Samurai warrior history. JT took a deep dive to try to get to the bottom of the meaning in BJJ and its origin- where did it actually come from?
With references from all corners of the internet the boys go through a wide ranging discussion to reveal if you should or not use it and maybe it has been replaced?
As Jiu-Jitsu culture evolves both terminology and procedure change and the question is has OSS gone the way of the dinosaurs?