THAT'S What I'm Talking About

   Randall mentioning the lowestar, and the recent catchphrase thing, got me to thinking again about the origins of this oft-repeated phrase.
Usually, I hear it when something has gone particularly well, the
speaker has received something just as they had hoped or better. An
enthusiastic affirmative. Example, I ask for a pen and a very nice pen
is offered to me, I am then told "Keep it". Woo-hoo, yay eee YAY!!
Now, THAT'S what I'm talkin' about!

   I also find it related to the phrase "YouknowwhutI'msayin?", which is usually uttered repeatedly by people that seem to need reassurance
every other sentence that they are getting their point across.

   I pulled aside an aquaintance recently and asked her did she remember the episode of "Diff'rent Strokes" where Willis finally had enough of Arnold asking him what he was talkin' 'bout and he shoved him in the street to be run over by a cab. He leaned over the crumpled heap in the street and screamed over and over "THAT'S WHAT I'M TALKING ABOUT!!" until the ambulance arrived. She didn't remember it, I may have made it up; if not it is the origin of the phrase. --r-
What is your favorite word?