In the aviation community, gouge is information that is passed on that is used as a study aid in preparation for any of the events that you may need to study for. There is a lot of written gouge out there, that covers the material in many of the tests you are going to to take along the road to wings. Gouge can also be word of mouth pass down that you will recieve in the ready room, like "watch out for this, or you had better know this", etc... Just an overall gereric term for passing advice, words of wisdom, or in the form of actual notes on subjects.
The flip side, the saying that goes with gouge, is "Live by the gouge, die by the gouge". The gouge you may get from a shipmate is NOT NATOPs or whatever manual or class you are studying, and should NEVER be treated as the primary source. More as a supplementary source to make sure you got everything down pat the first time studying.
Hope that helps...