h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I think perhaps using the word 'like' in all sorts of ways also serves to lessen the intellectual credentials of the speaker. By peppering ones speech with 'like' an incorrect usage balances any actual meaning full statement after it with an essentially airhead statement of social inclusion. After all, watching Yankee TV brings the inescapable conclusion that it is not cool to be smart in US youth culture.
Also it slows spoken conversation down sufficiently that the listener is not liable to lose track. As part of this is also focuses attention on the only really relevant part of a person's statement. I imagine that this was very useful for the originators of this phrasing as they could concentrate on their nail polish or somesuch without having to concentrate on what is being said around them secure in the knowledge that on hearing the word like they have to tune in sufficiently to reply with 'Like, yeah I so totally know what you mean!' or other meaningless rubbish.