"I think a lot of guys, if you've dated a bit, have the benchmarks," says Adam Fulrath, 36, an art director in New York. Fulrath's came in the form of a savant-smart, busty blonde named Sharon. Sharon painted abstract watercolors of flowers, played guitar, drank with the liver-macerating zeal of Tom Waits, and liked to drag Fulrath on spur-of-the-moment road trips to sleazy motels—and bring a camera. But her control over her tidal emotions was tenuous at best. When Fulrath finally decided he'd had enough, Sharon decided she'd get him back by showing up at his apartment in only her underwear. But it was cold, so she slipped a pair of lace-trimmed aqua panties on over her jeans, and proceeded to walk the mile from her apartment to his doorstep. Fulrath was mortified.

He immediately took her back.

"We all like danger and spontaneity," Fulrath says, eight years later. "In this attention-deficit world, where you're constantly looking around, she would keep me on the ball—she would challenge me. I was never bored with her."

Let's be honest with ourselves about what's going on here: It's an undeniable fact that if Sharon hadn't borne such an uncanny resemblance to Jenny McCarthy, as Fulrath claims she did, she would not have had the same currency to expend on her eccentricities. This phenomenon only serves to emphasize that point: Would Zach Braff's character in Garden State have sat through an elaborate hamster funeral if his hostess didn't look like Natalie Portman?

But there's a certain gloss on these big-screen depictions that leaves out a key component of the Crazy Girl appeal: The closer to the edge she skates, the more enchanting she becomes. There is a gulf of difference between the quirky (She wears a helmet! She likes the Shins!) and the mad (Oh, fuck, oh, fuck. She's cutting herself again.)—a place inhabited by self-damaging ticking time bombs like Amy Winehouse. This is a dangerous place. It's in these rocky outcroppings that we find ourselves contemplating what it might be like to crash at a roadside motel with Lisa Marie Nowak, the diapered astronaut charged with attempted kidnapping. For your average repressed, career-driven shlub, the terra incognita that these women represent seems vaguely—liberating.

"I think underlying it all is sex," says David Rabe, playwright and author of Hurlyburly. "The sexual state seems more present, more up-close in that type of woman. There's something in that disheveled personality that says they're going to make that state more available somehow—deeper and more intense.

Long after Lawrence has shaken Hannah's spell, and his mom has confessed her secret fear that his muse would have one day "suffocated the children" had they ever gone down that road, he still can't stop thinking about her.

"[All the girls] I've met since her, in some way or another, have been the most spectacular girls on earth," Lawrence says. "Before I met Hannah, I would have died for any one of them. I met this girl who was a commentator on cable news—super-brilliant, very cute. We got into this relationship, and I all of a sudden found myself thinking, Why isn't she doing it? Why isn't she enough for me? I mean, this girl is successful, makes hundreds of thousands of dollars, travels all over the world, has half the U.S. Senate in her Rolodex, and that's not enough. Because she's not crazy."

Have you ever dated a Crazy Girl and are still alive to tell all?