05/26/2011 at 05:10 PM EDT
was ready to dance until the world ends! The actress threw her hands in the air after arriving at one of her favorite spots
, Trousdale Lounge
in L.A. Once she was at her table in the backroom, Greene greeted her friends with hugs. She seemed especially into the Britney Spears
tunes, and she jumped up and twirled around to the music with one female friend, refreshing herself with cocktails in between dances. Also in the backroom: a subdued Chris Hemsworth
, who was more interested in people-watching than dancing.
Before jetting off to Monaco
with new fiancée Kim Kardashian
, NBA star Kris Humphries
partied at SkyBar inside L.A.'s Mondrian Hotel at the monthly Champagne & Caviar bash. Humphries held court with guy friends, while Ryan Phillippe
was spotted near the bar with his pal Jesse Bradford
and David Arquette
bounced from table to table, mingling with friends.
sipped a namesake cocktail – the Diddy! – created especially for him at the Ciroc Cocktails with Jessica party inside New York's Hudson Hotel. The bash, which featured a customized cocktail menu, also drew out heavy-hitters in the music industry, as well as various deejays.
stepped out for dinner with a male friend at West Hollywood's Chateau Marmont
, where they were soon joined by two other guys outside on the patio. Despite the intimate setting, the group seemed boisterous at times, and McGowan would occasionally burst into laughter while sipping on wine.
KRISTIN BOEHM, JENNIFER GARCIA and DAHVI SHIRA