Kendra Wilkinson shook things up in a cleavage-baring yellow micro minidress while Kirstie Alley showed off her toned-up curves in leg-baring copper fringe.

Skimpy, cut-out and beaded costumes dominated the dance floor for a "Dancing with the Stars" competition night devoted to pursuing "Guilty Pleasures." Since the contestants were asked to perform to songs they were ashamed to admit they loved, revelatory frocks were in order.

"The dances definitely contributed to the sexiness of the costumes, along with many of the songs used tonight," the show's costume designer, Randall Christensen, tells StyleList.

Meanwhile, for the second time this season there was a ballroom spill as professional dancer Karina Smirnoff took a dizzying fall after tripping over partner Ralph Macchio's cape.

Christensen gives us some behind-the-seams dish on the mishap as well as the night's best looks:

Kendra Wilkinson: For her booty-shaking Samba the reality star and her partner, Louis van Amstel wanted "to express "Livin La Vida Loca" and beaded fringe did it," says Christensen. "Of course the cut of the dress -- sexy neckline, bare sides, micro miniskirt -- lent itself to those steamy nights in Rio de Janeiro." The look produced the desired reaction: Judge Bruno Tonioli described the performance as "attack of the killer boobs" and Wilkinson earned her best score.

Kirstie Alley: The 60-year-old actress recently proclaimed she's almost danced her way into a size 6 and the short, copper, fringe-accented Samba dress Christensen created was a celebration of her toned figure. "I love dressing curvy women and accentuating those feminine curves was a blast," says Christensen who used short bands of fringe to smother Alley's skirt with shades of copper and brown. "Kirstie is quite literally melting away and we are taking in her costumes every week. That beautiful transformation of slimming down by toning up is wonderful to witness." Ralph Macchio: Smirnoff told co-host Brooke Burke after a week spent worrying if Macchio could manage his dramatic paso doble cape, she tripped on it. Before performing in his royal blue, gold and hot pink opera jacket, "Ralph actually practiced with a cape skirt to familiarize himself with the extra movement the cape would make," Christensen says. And the couples' dress rehearsal went off without a hitch: "I'm always biting my nails during dress rehearsal -- which is only two hours before we go live on the East Coast -- to make sure the costumes function properly without interfering with the performance." He gave Macchio kudos for his "chivalrous recovery."

Chelsea Kane: Thirty-five yards of silk chiffon were used to execute Kane's vision of a flirty, bedazzled "schoolgirl on a field trip" dress.

Romeo: For his "Titanic" themed waltz, Christensen created a flowing, feminine, turn-of-the-century inspired multi-colored ballgown for partner Chelsie Hightower, while dressing the rapper in a replica of Leonardo DiCaprio's "Jack" costume. The ruched midriff and square neckline on Hightower's dress were in keeping with the couples' romantic vision.

For more "Dancing With the Stars" fashion scoop, catch up with last week's recap.