This study aimed to understand how people learn and teach informally in an anonymous online bulletin board, the primary purpose of which is not learning and teaching. We conducted a qualitative analysis of comments and replies tagged to the most popular postings of an anonymous online bulletin board, during the global economic crisis in 2008-2009. The bulletin board, Agora Economy Room, is housed in the Korean portal site, Daum. We found four interrelated collective activities--recognizing teaching presence, collaborating, labeling, and guarding--among the participants that made active informal learning and teaching possible. These activities had an effect on the characteristics of the emerging informal educative space in different ways. A conceptual map of the findings of this study is discussed as a conclusion. (Contains 3 tables and 1 figure.)