Inside the Hottest Star-Studded Beach Parties

"Extra" spotted her wearing nothing but the alcohol monitoring device and a skimpy red bikini at the beach in Malibu.

She stripped down for a photo shoot at the Boost Mobile Party at the Polaroid Beach House in Malibu, where she fired back at the paparazzi crowding the shore.

She whipped out her digital camera and started taking pictures of the photogs!

At the same party, Paris Hilton made the rounds in a white skull-print dress with her newest accessory: her new Yorkie pup named Cinderella.

Also at the party was a casually-dressed David Hasselhoff, who revealed his odd talent - hairdressing!

"Extra" spotted the "America's Got Talent" judge curling a woman's hair while she relaxed by the waves.

Just down the street, Victoria's Secret model Selita Ebanks glammed up the LG House, where fiancé Nick Cannon decked out guests in t-shirts to promote his "Stop Hating" campaign.

"We're trying to talk about unity in the community," explained Nick of the effort.

Meanwhile, thousands of miles away, the stars were partying in the Hamptons!

Debra Messing dazzled in Donna Karan while hosting a Mercedes-Benz polo match at the Bridgehampton Polo Club's Jet One Jets Field.

"Extra" also spotted special correspondents Katie Lee Joel and Beth Ostrosky, who revealed that lounging in the sun is just business as usual!

"We like to go out during the day. It's beautiful!" Katie Lee said.

Kim Kardashian and Shanna Moakler, dressed down in black, came to support a special cause at the Playboy Mansion.

Denise Richards hosted a luau there to benefit the Nicole Brown Foundation to Stop Domestic Violence.