There exists a plethora of information and communication channels on the web which include a lot of sensitive conversations that people may like to be part of as an anonymous user. Several anonymous networks such as TOR provide this level of anonymity by masking the user's credentials and using one of the many exit nodes to connect to the end user (often a website). However, in case of misbehaviour via such networks, the only way to block such users is to restrict all the exit nodes of anonymous network. This would restrict anonymous access for behaving users as well. In order to resolve this issue, we propose Nymble, a system that supports anonymous blacklisting of misbehaving users. Nymble stays true to the core concepts of anonymous networks such as anonymous usage, backward non-linkability while still providing a mechanism to selectively block misbehaving users. This system is scalable and performs at speeds that is suitable for standard web usage. Our system is thus agnostic to different servers 'definitions of misbehaviour — servers can blacklist users for whatever reason, and the privacy of blacklisted users is maintained.