Samantha Ronson performed a sexy lap dance for Lindsay Lohan. The DJ – who was playing a set at exclusive London night spot Chinawhite on Wednesday – treated her ‘Mean Girls’ star girlfriend to the saucy routine as Katy Perry hit ‘I Kissed a Girl’ was played.

Samantha – who is the sister of music producer Mark Ronson – gave the impromptu erotic dance after becoming jealous of other girls flirting with Lindsay. A source said: “They went into a full kiss, their hands all over each other. Nobody knew where to look.”

Earlier in the evening, Lindsay had ordered several girls away from Samantha’s DJ booth after she spotted them handing over their phone numbers written on the back of drinks receipts. The source added: “Lindsay crawled on all fours under the bar and nestled up to Sam on the decks, hugging her as if to say she was her girl.” Lindsay’s ex-boyfriend Calum Best – the son of late soccer legend George Best – was also at the event, but kept his distance from his former lover.

As the stars left at 4am, a fight broke out outside, prompting Lindsay’s minders to desperately fend off fawning fans. Lindsay said: “I’m OK, I’m a big girl, I can take care of myself.” She added of the chaos: “I just wanted to make sure everyone had a good time. I didn’t want anyone to get hurt. I’m so, so sorry.”

Lindsay and Samantha are reportedly set to fly out to Paris today to have two engagement rings made based on their own designs. They are expected to return to the UK to make an official announcement.

In September 2008, it was widely reported that Lohan confirmed she was in fact dating Ronson during the syndicated radio program Loveline. During the program, DJ Stryker asked “You and Samantha, have been going out for how long now?…Like two years, one year, five months, two months?” to which Lohan laughed, and replied “For a very long time.”

Lohan’s father Michael Lohan has been very outspoken in his disapproval of Lohan’s relationship with Samantha Ronson and on September 24, 2008, Lohan wrote a response to him via e-mail to the New York Post: “Samantha is not evil, I care for her very much and she’s a wonderful girl….She loves me, as I do her.”