A 'Shake-Off' Between Kirstie and Kendra on 'DWTS'

This week on "Dancing with the Stars" the theme was guilty pleasures -- and contestants Kirstie Alley and Kendra Wilkinson used it to their full advantage.

Wilkinson and partner Louis van Amstel bumped and grinded to Ricky Martin's "Livin' La Vida Loca." Judge Len Goodman commented, "The more you gyrated, the more I palpitated! I'm telling ya!"

Then Alley and Maks Chmerkovskiy tore it up with their Samba to the Britney Spears song "Baby, One More Time." Judge Bruno Tonoli said, "Your wiggly bum sends shockwaves through the airwaves!"

Watch their performances!

Backstage, Alley told "Extra's" special correspondent Tony Dovolani she's always loved Britney. "I remember when that song came out. She had so much confidence, so it actually gave me a little confidence. Come on, if she could do it when she's 12, you can do it now!"

And for her sexy performance, Alley explained, "You turn into a stripper a little bit when you see people appreciating you shaking your ass!" Maks added, "I think it was a shake-off between her and Kendra."

Wilkinson laughed, "It was Len's birthday tonight. I had to give him a birthday surprise!"

The two "Dancing with the Stars" duos find out their fate Tuesday on ABC!