I recently read about outflanking (silman's Reassess Your Chess). See the example given, where the white king has to enter f8, g8 or e8.  The king outflank Black by gaining the opposition then losing it.  However, the text does not give a practical example.  Can anyone offer a practical example perhaps from a game they played?

Well, I think that example is just to illustrate the principle, but the use of it comes up very frequently.  For instance, a common king-and-pawn endgame:

Wait, is this similar to triangulation?
I've vaguely heard of the term, but I don't really know what it is...

No triangulation is something like this: It's going from one square to an adjacent one with an extra move in between to gain the opposition.

I'll get it sooner or later, but ta!

I saw the same example in silman´s endgame course. dont you think that is the book you meant?

how about...