CARRIE UNDERWOOD pretty much made some 12-year-old kid's LIFE when she gave him his very FIRST KISS on stage at her show in Louisville, Kentucky on Saturday.  And the kiss was on the lips, baby.  That's what I'm talking about.

The kid's name is Chase . . . and there's a video of the entire thing that he'll surely show every one of his friends.  It starts with her asking him how he wants to do it.  Dude doesn't hesitate . . . he says, "Lip to lip."

After the show, Carrie Tweeted, "Thanks, Chase, for the kiss and thanks Louisville for rocking so hard tonight!  We had fun!