Diffusion of responsibility is a well-known effect widely studied in a real-life setting. It can occur in a situation in which the more people observe a crisis event, the less likely it is that someone will react and provide real assistance. These days of a galloping digital revolution a question is to be raised as to whether the same effect can be observed in the online space of communication. In order to investigate this phenomenon we designed a study aimed at testing whether people exposed to a situation of cyberbullying will decide to take action against it depending on how many other Internet users are also aware of that crisis. Results obtained by us confirmed the existence of the diffusion of responsibility in the Internet similar to that observed in our daily lives. We also confirmed that a well-known influence technique “Even a penny will help” (in our study “every reaction will help”) can be effectively used to model behaviour online. In our times of digital revolution, those outcomes can be a step both toward understanding human behaviour in the online setting, showing us that it is not that different from the one presented in real live face-to-face communication and toward helping deal with antisocial behaviour people face online on a daily basis.