You never know what you might learn from "The Ellen DeGeneres Show."

WWE newbie Ronda Rousey visited the show on Tuesday to promote her upcoming pro wrestling debut, and she had an interesting lesson to teach: Mean Mugging 101. The former UFC fighter and Olympian showed host Ellen DeGeneres how she learned to make such intimidating faces, and it's actually impressively simple. DeGeneres tried it out herself, applying what Rousey learned from her godfather as a little girl.

"You look through your eyebrows," Rousey said, demonstrating the look.

DeGeneres followed her instructions, and the results were pretty fantastic. Watch below, starting at 5:00.

The visit was not just entertaining for the audience; Rousey shared how much fun she had in an Instagram post, writing that the talk show host is "just amazing" and thanking DeGeneres for having her back on the show.

For as mean as she can look, Rousey is quite the gracious guest.