All Paris Hilton had to do last night for her old friends at Heatherette was sashay down a runway.

When you're coming off a booze-fueled bender, however, that's a daunting proposition. Hilton—who, along with Britney Spears, Kimora Lee Simmons, and Lydia Hearst, had agreed to walk for front-row B-listers Cuba Gooding, Jr., Keith Urban, and J.C. Chasez—called in 45 minutes before showtime to say, well, she wouldn't be making it. (Spears actually showed up, but split once she saw the gong show backstage.)

The party line was that Hilton was home sick with a nasty case of "food poisoning." A source who was with her Monday night put it another way:

"She was doing tumbler shots of tequila till 3:30 a.m. at Butter, puked, and went home really sick. She must have been totally incapacitated the next day."

Also curiously absent: Heidi Montag, lead vixen on MTV reality show The Hills. While costars Lauren Conrad and Audrina Patridge were seated front and center (they've been joined at the hip all week), Heidi's been MIA.

"She just wanted to stay in L.A. and hang out with Spencer," Audrina explains. Huh. From the look of last night's show (this reporter never misses an episode), it seemed as if Heidi and Spencer were splitsville.

"Well, they've worked things out. He's even, like, helping her out on this album she's trying to do. Wait. I mean ... you're just going to have to watch the rest of the season!"

Thanks for the spoiler!

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