To understand what I mean by multiple levels of sharing, let's take a look at this crappy graphic below. In the graphic, you will see that stickman one on the left came up with something brilliant. Who knows, maybe it was a way to look different from one another. He shared it with a core group of stick friends and followers he has a first degree connection with. Sharing content through first degree connections maximize the chance for viral effect because these people care about what you have to say. This is important in viral advertising.
So... he shared it with his stick followers on Facebook and they liked it.