She's bubbly and beaming, high-volume, with a flip of dark hair and a face like a lollipop. She irks as she endears, bemuses as she bewitches. She's a bundle of energetic contradictions, bursting here, retracting there. Her expressions blink and change like a neon sign. Her eyes are popping globes. And she just sold you a bunch of car insurance.

Flo is her name. She's the spokeswoman for Progressive Auto Insurance, lighting up televisions in a series of commercials seen on WSB-TV Channel 2 in which her perky cashier pitches the money-saving merits of Progressive to customers. She works in a sterile, all-white big-box store, and her florid makeup stands out like paint spilled in snow.

First she caught our eye; now she's snatched our heart. Viewers are smitten. They're crushin'. They want to know: Who's that girl?

From a recent blog at HoustonPress.com, with the headline "The Cult of the Progressive Car Insurance Chick":

"Am I the only one completely and totally enamored of the woman in the television ads for Progressive car insurance? You know, the ones starring that babelicious brunette named Flo with her 'tricked-out name tag' and her '60s style eye makeup and her kissable red, red lips?"

No, sir, you are not. There's more where that mash-note came from, out there in the blogosphere's infinite confessional space: "She's hot." "She's weird but, God, she's fine!"

Others have naughtier ideas that they're perfectly comfortable sharing with the world, even if we can't do so here.

"It's so weird," says Stephanie Courtney, the actress who plays Flo.

We spoke to Courtney because we had to. We had to know if she was real or just a cartoon character. If she was at all like the effervescent Flo. If she really wore that much make-up and, hey, who does your hair?

Courtney, 38, has been playing Flo for about a year, and was recently signed to do 12 more Progressive ads. Which makes her the face and voice of Progressive, a peer of the Geico gecko (do they ever hang out, compare rates?) and the Verizon guy. She follows in a heady tradition of corporate mascots, from Palmolive's Madge to Tony the Tiger.

It's been quite a ride for Courtney, a senior member of famed Los Angeles improv troupe the Groundlings. (Courtney and the group performed in September during the Out of Bounds Improv Sketch Comedy Festival in Austin.)

It began with a simple audition for a commercial last fall. She showed up in a polo shirt and ponytail. She did some improvisation.

"They wanted someone with a lot of personality," Courtney says by phone from her Los Angeles home.

They liked her and signed her.

Then, the look. That look.

They cut her hair, gave her bangs. They subjected her to two hours of hair and make-up.

"They tease my hair, spray it and stick the headband in it," Courtney explains.

"And the makeup is like painting a portrait on my face," she says, laughing. "It's insane. It totally changes things on my face. It's like having a mask on."

One of Flo's best-known lines is: "Wow! I say it louder." (You had to be there.)

Courtney has popped up in the movies "The Heartbreak Kid" and "Blades of Glory," and was one of four leads in the smart adult comedy "Melvin Goes to Dinner," which won the audience award at South by Southwest in 2003. She also has a recurring role as a gossipy switchboard operator on the hit show "Mad Men." And you can see her doing yoga in a new Glade commercial.

How much is Courtney like flamboyant Flo?

"It's me at my silliest," she says. "You start off with a script, but at the end they usually let me put a little zinger in there. We put a little mustard on it. That's when it gets fun.

"Flo could be one of my improv characters, always on and sort of cracked in a weird way."

But who is Flo? What is she? People wonder ...

Like this blogger: "Is it her fabulous comic timing, her over-the-top facial expressions, her cute-as-a-button retro flip? Or is it the slight hint of a bad girl that lies just under the surface? The promise of a tattoo under that checkout girl uniform? The possibility of a motorcycle parked out back?"

Her character has been compared to a vintage Vargas pin-up girl, '50s burlesque dancer Betty Page and, adds Courtney, a "fetish chick."

"I don't know what it is," she says. "The way I play her, she's pretty much the most asexual thing on TV right now. I think the Geico lizard puts out more sexual vibes than Flo does. But I do think the cavemen are totally crushable."

Though Courtney is engaged to a sixth-grade teacher, Flo appears alluringly single. So pine away, in the same brunette-crush way you did with Mary Ann on "Gilligan's Island" and Velma on "Scooby-Doo."

Because things couldn't get much stranger than they already are for Courtney. Top this: People are dressing up as Flo for Halloween.

"That makes me so happy. But I do have to warn them that it takes two hours in hair and make-up," she says. "I wish them luck."