Hollywood is a pretty incestuous place, and with all that hooking up going on, it's not surprising that some very odd combinations have occurred. And quite a few of those couplings happened so long ago -- or were over so quickly -- that they often escaped mass media attention.
So in honor of Valentine's Day, sit back, put on your best WTF expression, and take a look at our list of the most twisted celebrity pairings ever.
Kim Kardashian and Nick Lachey
Kim and Nick hooked up just six months after he and Jessica Simpson called it quits. It didn't last, but that's okay. He eventually found love with fellow D-lister Vanessa Minnillo, while Kim got TV-married and is now attached at the attentionwhorish hip with Kanye West, with whom she's currently expecting a baby.
Justin Timberlake and Fergie
Before she made it big with the Black Eyed Peas, Fergie was part of the girl group Wild Orchid, which opened some shows for *NSYNC -- and that's how she and JT met. It was shortly before he started stepping out in stylish matching denim with Britney Spears and -- jailbait alert! -- he was only 16, while Fergie was 23.
Mariah Carey and Eminem
Eminem says he dated Mariah Carey for six months, and even rapped about their relationship on his album 'The Eminem Show.' She says it never happened, which led to a nasty and very public war of words -- but there's an awful lot of mutual hatred for it to be a total fabrication.
January Jones and Josh Groban
January Jones and crooner Josh Groban first got together back in 2003, when he was already a household name but she hadn't yet shot to stardom with 'Mad Men.' The romance lasted about three years, after which their respective publicists said they were "taking a break." Several years later, it seems break time's still not over.
Courtney Love and Ed Norton
The unhinged singer and the respected actor met on the set of the 1996 film 'The People vs. Larry Flynt,' and the mismatched couple dated for an astonishing three years. Despite once calling him a father figure to her daughter Frances Bean, she later turned on him -- because the multi-year relationship just hadn't punished him enough.
Cher and Tom Cruise
Cher and Tom Cruise first hooked up in the '80s. He was 16 years her junior and his career was just blossoming, but the ageless singer admitted that she was nevertheless crazy about him. He rarely talks about their time together, so maybe it was all for publicity. Or maybe she was just the first of his many beards.
Ashley Olsen and Lance Armstrong
After the disgraced cyclist ditched longtime love Sheryl Crow, he hooked up with bag lady-impersonator Ashley Olsen. Witnesses reported they publicly made out at a New York City bar one night in 2007, but after their PDA session, the two were rarely seen together again.
Chelsea Handler and 50 Cent
Chelsea didn't try to hide her pairing with rapper 50 Cent in 2010 -- she talked about it frequently on her show 'Chelsea Lately,' and often tweeted out pics of the two of them together. But it wasn't long before they had a pseudo-fight over an ex-girlfriend, after which Handler called Fiddy something offensive (go figure) and the relationship was kaput.
Amanda Bynes and Seth MacFarlane
'Family Guy' mastermind Seth MacFarlane and everyone's favorite demolition derby driver of late, Amanda Bynes, met in 2008 after she did a guest-spot on his so-wrong-it's-right animated show. They never confirmed the relationship, but at a party he referred to her as his "date" to a reporter, and bystanders said they left the event together.
Natalie Portman and Moby
Moby surprised a lot of people in 2008 when he told the New York Post that he'd had a "very brief affair" with Portman some time before. It makes a weird sort of sense that the two brainiacs would converge, but it had its dangers. Moby said his fellow nerds were enraged, adding, "You don’t date Luke Skywalker’s mom and not have them hate your guts."