If, as the old saying goes, you are known by the company you keep, then Paris Hilton should probably consider finding some acquaintances who haven't co-mingled their genes with tragic, train wreck blondes.

The jailbird would-be philanthropist marked the end of 2007 in Las Vegas, where she spent quality time with Kevin Federline, the custody-winning ex-husband of her frenemy, Britney Spears, and chatted up Larry Birkhead, the custody-winning baby daddy of the late Anna Nicole Smith.

Let's start with Federline, who has been on his best behavior since his 2006 split from his unsound, court-monitored former meal ticket. He was spotted with Hilton three nights running, starting on Saturday when they sampled the scene at hot spot LAX before hanging out in her hotel room, reports People.

(That buzzing sound you hear? It's an irate Brit-Brit firing up the hair clippers for another be-balding.)

But the mag says the gruesome twosome wasn't quite as friendly Sunday evening at Pure nightclub, only coming together long enough to quaff a tequila shot.

Other outlets, however, claim their interaction involved a little more than just a salt lick and lime squeeze.

Us reports Hilton, who has lately been back on the arm of well-chiseled onetime pizza boy Alex Vaggo, sidled up to the unwisely faux-hawked Federline and gave him "a warm hug and a kiss on the cheek," followed by five minutes of whispering and giggling.

"Kevin couldn't keep his eyes off Paris all night. He thinks she is a pretty cool chick," says a FOXNews.com operative, while a K-Fed buddy chimes in to Us, "Brit's going to blow a fuse."

PageSix.com, however, has a slightly different version of their cozy confab.

"Paris whispered some pretty sweet and enticing words in Kevin's ear," says a Federline source. "She basically asked him where he was staying and if he wanted to visit her in her own suite."

Then, in what can only be described as a worldview-shattering move, the never-was rapper-turned-PR-redeemed family man purportedly gave Paris the brush-off, a response that, if true (still a very big if), likely left a jagged crack in her once rock-solid self-esteem.

Still, the oh-so-optimistic Federline friend adds to the paper, "It will not be so easy to deny her next time."

Meanwhile, could K-Fed's Sin City goings-on prompt Britney to start buzzing her lawyers?

So says the Page Six mole, who maintains, "Britney got angry with Kevin for going to Vegas. She threatened to use it against him in court. She is really looking for anything on him."

Of course, Federline can always argue that he was just earning an honest wage as host of club Tangerine's New Year's Eve bash, although that wasn't the only holiday party he hit up.

Paris shows Larry how, like, totally cool it is that her dress shows where her heart would be.

He also put in an appearance at LAX, where Hilton was co-hosting a soiree with sister Nicky for a reported million-dollar payday. According to Page Six, Paris worked hard for the money as she entertained the crowd with her "best stripper moves" and planted a kiss on her little sis.

While catching her breath between gyrations and smooches, she posed for pics with Federline and Birkhead, who was snapped talking into her ear, presumably regaling her with tales of daughter Dannielynn's latest TV and magazine appearances.

But it turns out Kevin and Larry (are we the only ones picturing a reality show centering on the misadventures of a pair of employment-challenged single dads?) weren't the only ones graced with Hilton's company over the weekend.

TMZ.com reports she also got her flirt on with semi-famous reality stud Brody Jenner, who was also seen in Miami on New Year's Eve eyeballing Mandy Moore (per FOXNews.com).

And just in case you thought she'd forgotten her post-prison promise to use her celebrity for good, she did just that by devoting several whole minutes Saturday night to helping the differently abled, says TMZ.com, which in Paris parlance means she gave a lap dance to a hot young guy in a wheelchair.

Next: Quickies: Miley Not So Smiley, Pam's Problems