"Formidable-femininity" is a type of women's gender performance that I found in a woman's self-defense class. As a kind of gender performance it differs from "conventional-femininity" in that it lacks those characteristics commonly associated with women: docility, passivity, and weakness. It does, however, involve qualities such as feminine fashion and sex appeal. Using gender performativity theories, Ethnomethodology and Practice Approaches I indicate ways in which it demonstrates women's social roles related to patriarchal power structures and "rape culture" gender arrangements. I, furthermore, identify ways in which these performances redefine "femininity" as they are constituted with fighting, feminine fashions, and "sexiness," thus, women can be both "feminine" and "formidable." In this way formidable-feminine performances can be a form of feminist activism called "gender play," enacting the third wave agenda of female power, gender fluidity, and women's independence.