By its very presence we are reassured that additional things lie behind our current view and that they will be exposed by a single tap. In short... the hamburger icon is a simple universally understood metaphor for displaying further menus & navigation.
So how did we come to this collective understanding? Who originally thought that three horizontal lines was a sufficient way of depicting the menu behind it?
I think that whoever invented the hamburger icon deserves praise for creating something so simple and yet so useful.