Her friend said that women and men are treated the same. Then he saw her tip somebody.
They said she was betraying her culture. They said she'd intimidate men. They said she was angry. And she said, "Yeah?"
The whole talk is 100% worth your time, but I'll try to sum up.
She spent her whole life being treated like she was less valuable than a man.
From the time when she didn't get to be class monitor because that job was only for a boy, to the time when she tipped a man and the man thanked her male companion, Adichie has a lifetime of stories that show how far we still have to go to achieve some semblance of gender equality.
"I am angry. ... We should all be angry. Anger has a long history of bringing about positive change."
As she grew up, she had to respond to people who insisted that feminists are women who aren't happy. Or who hate men. Or who are corrupted by Western influences.
She believes that we all should be feminists and that, by embracing that paradigm, we can be more true to who we are.
"The problem with gender is that it prescribes how we should be rather than recognizing how we are."