Lindsay Lohan has turned to caffeine for her latest kicks, and spent the holiday downing can after can of Red Bull.

The newly sober starlet -- who was banned from drinking alcohol by a judge and ordered to wear a Scram monitoring bracelet -- partied with pals including British actress and reality star Lady Victoria Hervey during Memorial Day weekend.

Friends say Lohan lives on eight cans of Red Bull a day, followed by Coca-Cola, and chain-smokes cigarettes. After spending Saturday sunbathing with Hervey at Pacific Palisades, she tweeted: "Red Bull and waters and work -- my new bff's hehe. Everyone should try it! It's more fun -- you'll see."

Lohan and aristocrat Hervey -- who is set to appear in the next season of Tinsley Mortimer's show "High Society"-- have become close friends after hanging out together at the Cannes Film Festival.

Sources tell us Lohan, who kept her alcohol-monitoring bracelet covered up under a pair of knee-high boots, is really trying hard to mend her ways. One told us, "Lindsay finally realizes the seriousness of the situation she faces. She doesn't want to go to jail and she wants her career back. She is trying to surround herself with people who are a good influence instead of the usual enablers."

More On This...

Lady Victoria is said to be a good influence because she's seen the perils of drugs. Her half-brother John Hervey, the 7th Marquess of Bristol, was a heavy drug user and died in 1999 of AIDS-related illnesses.

But Lohan's new clean act has yet to open doors for her in Hollywood. She tried to check into the plush Sunset Tower Hotel for the weekend, but was refused. An onlooker told us, "The front desk manager told Lindsay they were full. But she wouldn't take no for an answer and kept insisting the Internet said there was room. She even insisted the front desk call the owner Jeff Klein, but he was not available, and was again told 'Sorry, no room.' So she stormed off."

Go The New York Post's Page 6 column for more celebrity gossip.