Know what’s cool? When actual rappers rap. You know what’s not cool? “Mapping.” That’s a portmanteau I just made up for when moms rap. Or more specifically, Madonna rapping — like that painful Neptunes-produced poppycock she subjected us to on Hard Candy when she was all “see my booty get down.” And the “yoga and pilates and lattes” stuff. Real bad.

Another thing that’s not cool? Crappy mash-ups like the type your boyfriend thinks he mastered just because he spent 30 minutes looking at Ableton Live.

Which brings me to my next point, which is that Katy Perry’s live VMA performance of “Like a Virgin,” backed by Travis Barker and DJ AM, will feature neither embarrassing rapping nor half-baked mash-ups.

When I first found out that DJ AM and Travis Barker are the official VMA House Band and are backing up Katy Perry with their DJ-n-drum hybrid duo, I was like what type of bizarro Bar Mitzvah entertainment experiment is this? And I also had the question-mark-over-my-head feeling when I found out that Katy’s going to be doing an updated version of “Like a Virgin” (the same song Madonna opened the very first VMAs with in 1984 and made out with Britney to in 2003). Not that Katy would ever trot out some crappy rap version of a Madonna song (leave that to Madonna!), but nonetheless, I wondered how she’s planning on improving upon a classic.

So I just watched Katy — in fluorescent neon high-waisted skinnies, white t-shirt with a leopard graphic on it, cute little pink ballet flats, and the shiniest of shiny hair that only fueled my hair envy, and no, Travis McCoy was nowhere to be seen — DJ AM, and a shirtless Travis Barker rehearse her performance on Stage 16.

Between takes, Katy fended off some pre-show nerves by doing the Running Man and the Robot, then rechecked the “Like a Virgin” lyrics on her Sidekick while AM, who was playing assistant director, joked that she was probably just Googling herself.

But, the bottom line here is that DJ AM, Travis and Katy are taking Madonna’s classic and updating it with such a perfectly of-the-now sound that it just might give the mother of reinvention a reason to hurl a phone into a wall. Seriously, Madonna should’ve just given AM a call.

+ Just in: exclusive video footage from Katy’s rehearsal:

Stay up-to-date on everything about the 2008 MTV Video Music Awards at vma.mtv.com, and don’t miss the big show Sunday (September 7) at 9 p.m. ET/PT or the pre-show red carpet coverage that starts at 8 p.m. ET/PT.