I've seen many sefarim that talk about finishing Shas, simply put, going through the sugyos and understanding them, even if you forget it. But what does it mean to "know Shas"? Does that mean I know word for word by heart? Is it the Concepts you know really well? Is it the tosfosim you've got down pat. What does it mean when one says, he "knows Shas". Sources Please
Yeshivish has many ambiguous terms. This is one of them. I've heard this used by yeshiva students as well as rabbis / teachers and from what I can tell, there's no consistency in its meaning.
It could mean:
You've memorized all of Sha"s. Not necessarily word for word (though, I met one person years ago who, as far as about 50 people could tell, he really did do that.), but you know where things are. I.e., if someone mentioned a topic, you know exactly which page of which masechta (tractate) to find it.
You know and understand the various sugyot ("topics" out of lack of a better term) in sha"s. This includes all the arguments and discussions as well as all or most of the "major" commentaries explanations (Rash"i, Tosfot and perhaps a few of the other notable ones such as Ras"h, Ri"f, etc.) I've heard this idea used to mean every masechta or most of them.
There are probably other explanations of this term, and others are free to add or edit this list. However, the above are the main two that I can think of, now.
Incidentally, there is a book called "Yeshivish". I don't know if this term is mentioned there; I have the book home, and I'll try to find it. But, in general, there is no official "source" for yeshivish terminology. Also, the language (according to the book it is considered a "language" as it is a form of communication mainly within Jewish learning circles and mainly in U.S. and a few other English-speaking countries.)