Before diving into her Class Day speech on Wednesday, Facebook COO Sheryl Sandberg promised Harvard graduates, “I can’t be as funny as Amy Poehler, but I am going to be funnier than Mother Teresa.”

The Lean In author returned to her alma mater to address seniors as part of the university’s annual Class Day ceremony. On stage at the Tercentenary Theatre, Sandberg reminisced on her undergraduate days at Harvard and graduate days at Harvard Business School, jokingly dating herself a bit.

“I never could have predicted Facebook,” she said, “because there was no Internet [then], and Mark Zuckerberg was in elementary school — already wearing his hoodie.”

Prior to joining Facebook in 2008, Sandberg served as a senior official in the U.S. Treasury Department, as well as Google’s vice president of global online sales and operations. Reflecting on her own career, she reminded students there is no such thing as a linear path.

“There is no straight path from your seat today to where you are going,” Sandberg told the graduating class. “Don’t try to draw that line. You will not just get it wrong, you’ll miss big opportunities. And I mean big — like the Internet.”

In fitting form, the chief executive, known for inspiring women to step confidently into leadership roles, addressed gender equality, saying:

We don’t always see the hard truths, and once we see them, we don’t always have the courage to speak out. When my classmates and I were in college, we thought the fight for gender equality was won. … Sure, most of the leaders in every industry were men, but we thought changing that was just a matter of time. … We didn’t need feminism, because we were already equals. We were wrong; I was wrong. The world was not equal then, and it is not equal now.

Only five percent of Fortune 500 companies are run by women. Although that number is on the rise, Sandberg added that women are still called “pushy” and “bossy,” while male peers are referred to as “leaders” and “results-focused.” Sandberg told students they can challenge stereotypes, sharing the slogan emblazoned on her new favorite sign at work: “Nothing at Facebook is someone else’s problem.”

“I hope you feel that way about the problems you see in the world, because they are not someone else’s problem,” Sandberg said. “Gender inequality hurts men along with women. Racism hurts whites along with minorities, and the lack of equal opportunity keeps all of us from fulfilling our true potential.”

Sandberg warned the Class of 2014 she was going to put pressure on them “to acknowledge the hard truths, not shy away from them and, when you see them, to address them.” She followed:

The first time I spoke out about what it was like to be a woman in the workforce was less than five years ago. That means that for 18 years, from where you sit to where I stand, my silence implied that everything was OK. You can do better than I did, and I mean that so sincerely.

She also took some pressure off, however, reminding students that they don’t have to know what career they want right now or how to get it.

“Most people who make great contributions start way later than Mark Zuckerberg,” Sandberg acknowledged, ending with humor. “And tomorrow, by the way, you get something Mark Zuckerberg does not have — a Harvard degree.”