In this paper, I reflect on a specific product of interaction design, social networking sites. The goals of this paper are twofold. One is to bring a feminist reflexivity, to HCI, drawing on the work of Judith Butler and her concepts of peformativity, citationality, and interpellation. Her approach is, I argue, highly relevant to issues of identity and self-representation on social networking sites; and to the co-constitution of the subject and technology. A critical, feminist HCI must ask how social media and other HCI institutions, practices, and discourses are part of the processes by which sociotechnical configurations are constructed. My second goal is to examine the implications of such an approach by applying it to social networking sites (SNSs) drawing the empirical research literature on SNSs, to show how SNS structures and policies help shape the subject and hide the contingency of subject categories.