Wikipedia is well-known as the fundamental encyclopedia of our times, and has become the primary source of information on the web and beyond. Nevertheless, the same strength of Wikipedia (its social collaborative nature) is also its Achilles' heel: every page in Wikipedia is the by-product of a social interaction, and can often degenerate into a battle among different opinions, biases or interests. In this paper we give a first introduction to Negapedia, the negative version of Wikipedia. Negapedia aims to uncover the hidden world behind Negapedia, exposing the negative layers of conflicts and polemics that make up for every single page. We give a panoramic of the system, showing its main functionalities and the challenges behind its creati...