While the boozy crowd readied itself for four minutes of awkward singing, the woman – “Karen” – suddenly belted out exquisite, pitch-perfect renditions of the Jewel songs “Who Will Save Your Soul” and “Foolish Games.”

Astonished crowd members picked their jaws off the floor and cheered wildly. One person was heard comparing Karen to “an American Susan Boyle.“

Unbeknownst to them, they had been victims of “undercover karaoke.”

Karen really was Jewel, and the proceedings had been filmed by FunnyOrDie.com, the comedy video website co-founded by Will Ferrell and Adam McKay. The video was posted Tuesday and was rapidly circulating online, with more than 160,000 views as of evening.

“I was a bit nervous to do this skit at first because I feared it would amount to little more than showing off some vocals, dressed as someone else,” Jewel said in an e-mail. “I was worried it wouldn’t be self-effacing enough.”

For the video, created by Funny or Die writer-director Eric Appel, Jewel was given a prosthetic nose, wig and glasses, and butt padding. Only after performing as Karen did Jewel return to the stage of the karaoke joint, the Gas Lite, as herself.

(Before the reveal, one audience member says to the camera: “They tell me she only sings at Christmas parties.”)

Though Jewel is principally a singer-songwriter, she has acted before, most notably in the 1999 Ang Lee film “Ride with the Devil.” This performance was quite a bit quicker (Funny or Die contacted her just a few days before taping on June 28) and more comical.

“This did not require much, as the costume did most of the work for me,” said Jewel, whose full name is Jewel Kilcher. “I love improv and this was a small chance to do that, luckily as someone else. I would love to do more of it in the future. A dream gig would be a show like `Curb Your Enthusiasm.'”

Jewel also shot another video for Funny or Die that she says involves former Alaska Gov. Sarah Palin. A spokeswoman for the site said it will be released next week.