The worst phrase in the world "you know what I'm saying "
Is difficult to avoid saying this sometimes. It's borne of frustration through not being able to articulate something clearly enough.
I live in Australia and it's use is rampant here amongst some younger people, as much as the rising inflection was/is ubiquitous amongst older folk.
I think it is said (unconsciously) for two reasons; first, to gain approval (as is the rising inflection) and secondly; to block the opportunity for others to say something. And that is why, for an old know-it-all like me, it is so bloody annoying!