Lohan and Ronson on Lohan's 22nd birthday
07/03/2008 AT 08:00 AM EDT
turned 22 Wednesday night with an intimate prom-themed birthday bash – and a sweet smooch from Samantha Ronson.
The actress – wearing a bright pink strapless micro-minidress by Bradley Bayou and an elaborate diamond necklace – arrived at Teddy's lounge inside the Hollywood Roosevelt Hotel
just after 10 p.m. And her companion Ronson took the prom-theme seriously, dressed to the nines in black pants, a tuxedo shirt, bow tie and top hat with red trim.
Once the 50 guests – including former Sopranos
star Jamie Lynn Sigler and Lohan's younger brother Michael – began arriving at the balloon-filled venue, the Birthday Girl greeted them all energetically with smiles, hugs and kisses. Ronson was never far behind, often keeping her hand on the small of Lohan's back.
Just after midnight, Teddy's wheeled out a large pink sheet cake featuring a picture of Marilyn Monroe in her iconic wind-blown white dress. The entire lounge sang "Happy Birthday" and Lohan obligingly blew out the candles. Her friends then chanted "speech, speech, speech," but the guest of honor replied jokingly, "Shut the f--- up." (Her mother, Dina, stepped in to say, "Thank you all for coming.")
Soon after that, Ronson took over the D.J. duties (replacing DJ AM), as she spun a mix of '80s tunes and current hits. Lohan – who stuck to Red Bull all evening – made several visits to the booth and pumped her fists in the air to Journey's "Don't Stop Believin'."
As the party wound down, the couple appeared to relax, even sneaking in a small peck on the lips at the DJ booth. By 1:15 a.m., the music was muted and Lohan turned out the lights with Ronson by her side.