Cee Lo, Lil Jon and Samantha Ronson were a handful of guests who hit NYC hotspot Greenhouse Thursday night to celebrate the birthday of the club's GM Barry Mullineaux and the 40th birthday of Lil Jon himself!

Check out our favorite photos of the night, above.

[Photos by Whitney Young of whiticisms]

Poison Ivy recently spent a Friday night at 92Y Tribeca with Lucinda Black Bear's Christian Gibbs, Chad Hammer and Mike Cohen.

We chatted with the boys about the musical impact of New York, how it feels to cover Springsteen in New Jersey, and why they wish it was winter all year round.

Check out our highlights, above!

Friends, now's the time to enter to win a pair of tickets to see Sister Hazel at Irving Plaza on Thursday, January 20!

Just follow us on Twitter and fill in this form.

XOXO

We were absolutely blown away by this video of Jessie J performing "Who You Are" in NYC's subway system!

"Performing is where I feel most comfortable," says the "Party in the USA" writer, who sang as a part of Giant Step and Arcade44's Boombox series.

"I love the reaction of people. Some people might put their fingers in their ears... Some people love it, some people cheer, some people leave. And it's good. It's nice. I like honest reaction. And that's what I think I get."

Check out Jessie J's serenade, above.

Zac Efron took a break from his action-packed week to show support for his cousin Emily Hobson, diagnosed with cancer in 2009, at the H.O.M.E. Foundation's celebrity video game challenge at Spot 5750 in Los Angeles Tuesday night.

"When he heard I had cancer, he immediately went in support mode," said Hobson, who was diagnosed with a rare type of tissue cancer called Sarcoma in May 2009.

Efron battled Super Bowl champ Michael Strahan at a game of Madden Football to support the I'm Too Young For This! Cancer Foundation, while Strahan played in support of the Intrepid Fallen Heroes Fund.

Poison Ivy first saw Ryan Star perform back in December at PLJ's Holiday Bash, and his brilliant voice and stage persona made us instant fans!

Having said that, we are beyond excited to present our next concert giveaway: two tickets to see Ryan Star at Webster Hall with special guests Hot Chelle Rae, Hesta Prynn and Gambit January 18!

Just follow P.I. on Twitter and fill in this form to enter.

Special thanks to Atlantic Records!!!

"What we need is a reality show about junkie vampires who have eight children desperately trying to lose weight in a bad economy."

-Brad Walsh Tweets