that's what i'm talking about 

Something you say when you see something really cool, or a hot girl walks by. You can say it even if you never talked about the subject before.

Two dudes sitting around.
15 minutes of silence
Dude #1: "Look at that chick!"
Dude #2: "That's what I'm talkin about!"

that's what i'm talking about by whodey June 15, 2004

that's what I'm talking about 

expression of approval or anticipation

Dude 1: "Dude, check out the size of that cheeseburger!"
Dude 2: "Now, that's what I'm talking about!"

that's what I'm talking about by Fronck June 2, 2008

Now that's what i'm talking about 

"Now that's what I'm talking about'!

'A catch phrase' commonly used to express 'enthusiastic support' for a particular 'subject/or subject matter'.

(With more of an emphasis placed on the word 'that's')
*acronym/abbreviated form: NTWITA or TWITA 'That's What I'm Talking About'.

Example:-

A guy just opened his first pay check- and he discovered, that the amount of money enclosed, was a lot more than he was expecting!

-> so he say's (while nodding his head in approval)~ 'Now that's what i'm talking about' !

Now that's what i'm talking about by Stump cap November 24, 2013

that's what I'm talking about 

Etymological note: This phrase can be heard in a recording of the (ca.) 1929 Fats Waller song "The Joint is Jumping".

"Get rid of that pistol, yeah, get rid of it... yeah... ha ha... that's what I'm talking about..." (from abovementioned recording, spoken)

that's what I'm talking about by Tyranny Sue August 3, 2008