Well, the spooky holiday coincides with Katy’s birthday (she turned 24 on October 25); so the singer threw a massive Halloween/birthday bash at Siren Studios in Los Angeles Tuesday night, reports E! Online.

Setting the tone for the event, so-gay Katy arrived at the festivities in a hearse, rocking a 10karat ruby and diamond necklace by jeweler Pascal Mouawad.

More than 200 costumed guests—including Josh Groban and Cisco Adler—packed into the Malibu Rum-sponsored event to creep each other out with their costumes.

Aside from guzzling rum concoctions, partygoers bobbed for body parts and made merry in a coffin photo booth and an execution chamber.

Guests were asked to dress as their favorite dead celebrity. Adorned with a bushy mustache, Katy resurrected deceased Queen frontman Freddie Mercury.

Good luck getting any girls to kiss you with that bristle-brush strapped under your nose.

Crowds packed the massive performance space and next door’s new hot spot Bardot to catch DJ sets by Steve Aoki, Danny Masterson, Shwayze (that counts Cisco Adler as one half of the colorful duo) and Mark Ronson.

Ronson, who ditched his fancier duds from the night before, rocked a red hoodie and square-framed glasses. Samantha‘s brother spun old school hits and even gave Britney Spears a shout out by remixing her hit, “Toxic.”

“Let’s hear if for DJ AM, the reason we’re all fucking here tonight,” Ronson told the audience.

That was certainly true of the vibe onstage. Celebuzz had an exclusive eye on the partying pals of Goldstein and fellow survivor Travis Barker (who was unable to attend due to recovery).

They included a bubbly Hilary Duff (enamored in conversation with Danny Masterson), a roving Macy Gray in a knit gray cap, nightlife kingpin Brent Bolthouse and the Black Eyed Peas‘ Will.I.Am.

The man of the hour, AM himself, arrived around 10:30 p.m., and hung in for a good few hours (despite the big gig in front of him tonight). While he didn’t spin, he certainly accomodated his fellow jockeys.

“AM was in great spirits,” the on-stage onlooker said. “He was constantly shuffling things around on the table, clearing wires, giving feedback, it was amazing. He was just getting back into the swing of things.”

Around 1:30 a.m. Goldstein, clad in jeans, a hoodie and a blinged out necklace, let out a yawn and was swept away by his publicist and two male pals.

Today he rests, as tonight he plays house DJ for Jay-Z, when the pair will help Live Nation reopen Hollywood landmark The Palladium.

The 2008 Video Music Awards kept that tradition going.

T-Pain was on a level all his own with his circus-like outfit and bling-blingity grills, while Pink reinforced her “I like to deviate from the norm” image with a jailbird inspired gown.

Some stars chose to leave their signature looks at home: Michael Phelps donned something other than his eight gold medals and Brit-Brit finally decided to give her messy bun a rest.

See what the VMA attendees were wearing in the gallery of 24 hits and misses.

Drop a comment whether you agree or disagree with the expert picks.

If you missed our last Cute Looks vs. Huh? Looks, take a look and compare.

Brooke Hogan, Cisco Adler, Seth Green and a bunch of other show-biz notables took time out before the VMAs to wax profane. Check it out below:

Holy [beep]! That was [beep]-ing insane!

Be sure to also check out Celebuzz’s exclusive interviews with the cast of Twilight, Brooke Hogan and Joe Francis from the red carpet of the VMAs.

In her defense, Cristiano Ronaldo is one sexy man. But that’s beside the point.

Paris might mean well, but when it comes to men (and her career), she just doesn’t seem to know her limits. In honor of her recent rejection, here is the countdown of Hilton hookups! Scroll through the lucky 13 and ponder why they chose her.