Ronda Rousey is a badass, plain and simple. She's a mixed martial artist, a judoka, an actress, and the first and current UFC Women's Bantamweight Champion. It goes without saying that there are few people in the world she couldn't take on.
Despite all that, because of her body and her profession, she gets called out by haters for having a strong physique that isn't what society likes to view as "feminine." It's a ridiculous notion, but there are plenty of people stupid enough to say it.
She's not stupid, though. She knows what they're saying and her response is awesome.