Call me a curmudgeon. There are just some expressions in today's vernacular that are just idiotic, and "That's What I'M Talkin' About" is one of these. It is so ghetto.
Several people are saying 'blah, blah, blah, de blah and more de blah..." Suddenly, a dimwit in the group hears something that dimwit didn't even mention but happens to like the subject and then dimwit blurts out, "Now THAT is what I'M talkin' about!"
The problem is, dimwit NEVER talked about the subject before it just came up and that same dimwit has just said "THAT" is WHAT it was talkin' about! Should dimwit say something like, "NOW THAT is something I would like to talk about," I would not have a problem, but dimwit acts as if dimwit was already talking about the subject that dimwit never even brought up!
This is lazy English, and I dun't lik lasy Englush.
Farkel