For Penny Johnson Jerald, one of the side effects of playing venomous first lady Sherry Palmer on the Fox series “24” is having fans stare her down to see if she really can smile.

“She’s a mouthful,” says Jerald of her character. “Every time I bite into Sherry, it’s like savoring a really good meal.”

The actress says she didn’t comprehend the significance of what she was getting herself into while they were working on the pilot. When the episode arrived on her doorstep, it opened a Pandora’s box of surprises.

“I had no idea that Kiefer (Sutherland) was in it,” Jerald says. “I thought ‘Oh my gosh, how innovative.’ The biggest surprise was when (my character) went to the point of pimping out her husband.” That would be David Palmer, the president of the United States, played by Dennis Haysbert.

Jerald’s list of credits includes regular gigs on “ER” and “The Larry Sanders Show.” She says she was always cast as an “easy-going, down-to-earth kind of brassy person,” though Sherry Palmer is apparently changing all that.

Jerald will next appear as national security adviser Condoleeza Rice in the Showtime telepic “DC 9/11,” now in pre-production. The rest of her time is spent at the L.A.-based Outreach Christian Theater Co. that she runs with her husband, Gralin Jerald; proceeds support the Arise Christian Center. It’s not the kind of thing one would expect of Sherry Palmer, unless there was a devilish twist.

And as for the role that Jerald says she’d really like to play, it’s that of the woman Sherry Palmer was patterned after: Lady Macbeth. “You want to see evil? That woman has no conscience whatsoever.”