Scholarly attention to hashtagging on social media sites has focused on their catagorization affordances. Grounded in the literature on online identity, this article examines how Tumblr users tactically use hashtagging architecture for publicity and privacy in self-expression. The analysis is based on Tumblr posts and their corresponding hashtags, combined with text-based, synchronous interviews with users. We find that participants use hashtags as a form of intimate expression, offering “secret whisper” spaces. Participants acknowledged a distinction between these spaces of intimacy and the more conventional space of the post. Extending on Goffman’s dramaturgical approach, we argue that this intimacy practice is a form of stage whispering, which is neither front- nor backstage, but implies and assumes intimacy while on the stage, as an actor might imply and assume intimacy stage whispering to her audience.