Facebook COO Sheryl Sandberg tells Cannes audience how she threw boss Mark Zuckerberg a 30th birthday party

WHAT happens when your 23 year old boss turns 30? Sheryl Sandberg reveals how tech powerhouses at Facebook are never too busy for cupcakes.

Facebook chief operating officer Sheryl Sandberg at the Davos World Economic Forum.

WOULD you throw your boss a birthday party?

When you’re Sheryl Sandberg, 44, and your boss is Facebook founder Mark Zuckerberg, 30, you bet you do.

For Sandberg it meant cupcakes and a reason for herself and others to celebrate the boss hitting that significant age barrier.

“I was so happy when Mark finally turned 30, he didn’t have a party but I did,” she told a global advertising and marketing conference in Cannes earlier today.

“There were cupcakes and I wore a hat all day.”

Zuckerberg was 23 when Sandberg joined him as Facebook’s Chief Operating officer more than six years ago.

Mark Zuckerberg was just 23 when Ms Sandberg started at the company. Pic: Ben Margot.

She said in that time he had “grown up a lot” and when asked about his personal characteristics, she said that people often underestimated him because he was shy. She said one of the best things about Zuckerberg was that he was a good listener.

“He is one of the best listeners. He will listen to what you have said, and what you haven’t said.”

Sandberg spent 45 minutes talking to an audience of 2000 people about the digital future and where Facebook is going. She called out Facebook’s mistakes, in particular, she said they had been slow to recognise the power of mobile.

“Mobile is bigger than we thought or predicted.” She also acknowledged that the ads on Facebook needed to improve. “I’m not sure every ad on Facebook is a delightful experience and we want to fix that.”

Yahoo CEO Marissa Mayer also appeared at Cannes but failed to engage the crowd.

The next hottest thing is messaging, according to Sandberg.

A long time champion of workplace diversity, and gender equality, Sandberg challenged the advertising industry to change the stereotypes of how women — and men — are represented in marketing. She said the idea of women showing leadership being described as bossy and pushy -while the same traits were accepted in men — had to change.

“Make women look happy when they are at work and men joyful when at home,” she urged.

“Change stereotypes and we can change the world.”

Sandberg appeared on the stage at Cannes the day after the woman once expected to be her biggest rival also spoke.

In the end, there was no contest.

Yahoo President and CEO Marissa Mayer read her speech from an autocue and failed to engage with anyone in the audience, leaving thousands to take to Twitter to complain about it.

Sandberg on the other hand, was the ultimate communicator and had the audience loving her.

Facebook 1; Yahoo 0.