The paper analyzes discursive practices used by Czech journalists on their Twitter accounts declared as private and their various (professional and non-professional) identities presented there. It follows from the material analyzed that despite declaring their accounts as private the journalists often use them to spread mass media content and refer to themselves as journalists. The most important discursive practices typical of social media communication are – according to the presented research – implicit comments in tweets which are not intelligible without recipients’ sharing of the author’s knowledge and/or attitudes. The analyzed accounts are of a hybrid nature in its essence: the identities and practices typical of mass media communication and the ones characteristic of social media communication are intermixed both in stable parts of an account (e.g. bio refers to one’s professional identity and background image to his/her hobby) and in individual tweets (e.g. a journalist reproduces a mass media text and at the same time comments it just by an emoji). Having analyzed above mentioned identities and discursive practices, the authors investigate how journalists reflect on their own activities on Twitter and how they argue for the private status of their accounts in interactions with other Twitter users.