OOPS: Jane Krakowski certainly knows how to titillate her audience. She’s famous for playing overly flirtatious characters such as Jenna Maroney on “30 Rock.” During the Tuesday night debut of her new cabaret act, “Jane Krakowski Has Sold Out…Tickets Available,” at Feinstein’s at Loews Regency, however, she may have titillated a little more than usual, thanks to an Yves Saint Laurent dress. The actress, who also wore Alexis Bittar jewelry and Brian Atwood heels, had to contend with a loose and shifting bodice. “I put an extra snap in there and just put my trust in Yves,” said Krakowski, who unveiled two new songs that night — a hilarious ditty about tweeting (to the tunes of “Zip” from the musical “Pal Joey”) and a hip-hop version of “Diamonds Are a Girl’s Best Friend,” with shout-outs to Tiffany & Co. and Cartier. Maybe her fiancé can offer some tailoring tips for the show’s weeklong run — Krakowski is engaged to men’s wear designer Robert Godley of the New York-based label Psycho Bunny.