Sean Penn and Charlize Theron Are 'All Over Each Other' During a Night Out
01/12/2014 AT 12:50 PM EST
The actress joined the list of some of Hollywood's most prominent stars to attend Penn's third annual fundraiser event at the Montage Hotel on Saturday night. And, unlike some of her peers, there was no need to voice her support – the couple let their hands (and lips!) do all the talking.
"[He] had his hands all over Charlize," an eyewitness tells PEOPLE. "During the event they were all over each other – it was on!"
Although Penn, 53, and Theron, 38, arrived separately, they were spotted holding hands as they walked away at the end of the evening together.
The longtime friends were first spotted getting cozy on a shared New Year's vacation to Hawaii.
Reporting by MATTHEW COLE WEISS