This article explores the phenomenon of block talk among Germanspeaking Twitter users, based on a subsample of 1700 tweets from a larger corpus of 380,000 block-related tweets collected between February and December 2021. Block talk refers to users publicly mentioning and conversing about the disconnective practice of blocking, which sometimes stimulates a debate about the legitimate use of blocking while at other times providing an outgroup marker for collective positioning. Through the example of block talk we demonstrate that the platform’s curatorial infrastructure for drawing boundaries between public and private is continuously negotiated, and that this negotiation transforms the meaning of some of the default communicative affordances of the platform but also creates its own routines of making public. On the one hand, we show how users adapt conversational devices such as hashtags, screenshots, and @-mentions in the context of block talk. On the other hand, we present examples of Twitter users’ normative reflections about blocking and discuss them as processes of metapragmatic enregisterment. In the final discussion, we propose to integrate processes of routinized adaptation as well as reflexive enregisterment into a joint process of ‘communicative infrastructuring’.