EXCLUSIVE: Read it here first...

Life's a Beach When Audrina's Boy Flirts With L.C.

Mon., Jul. 7, 2008 1:19 PM PDT by Marc Malkin

Audrina Patridge, Justin Bobby, Lauren Conrad

Simon Ferreira/startraksphoto.com, Jamie McCarthy/WireImage.com

Fireworks weren't only erupting in the sky on the Fourth of July.

Things apparently got a bit heated on Independence Day at the DKNY house in Malibu, where Audrina Patridge and her boyfriend, Justin Bobby, were hanging out with Lauren Conrad.

Yup, here's some more Hills drama for ya...

"Justin was very flirty with L.C., and Audrina got pissed," an eyewitness reports. "Audrina stormed off."

Bobby ran after her, asking, "What? What's wrong?" according to the source.

There was a Hills camera crew capturing their day at the beach, but unfortunately they weren't rolling during Partridge's oh-so-dramatic exit. (But maybe a Living Lohan crew got the footage. Dina and Ali Lohan were shooting their E! reality show at the house, too. I'm told Lindsay even made an appearance.)

However, Audrina and Bobby's spat seemed short-lived—the two were later spotted at Project Beach, also in Malibu, where they hung out with Stephanie Pratt. Also there were Tara Reid, Taye Diggs, Kourtney Kardashian and on-again couple Brody Jenner and model Cora Skinner.

—Additional reporting by Matt Donnelly