In the early years of kickboxing in the Netherlands, a number of fighters got involved in criminal activities. Literature typically focusses on social learning, but as the inner city of Amsterdam in the eighties provides a specific setting, this article particularly describes a historical process. In the qualitative data from interviews, observations, and various documents, three questions: Who were these kickboxers? Where did they enter the criminal circles? Why did they go along with what happened there? It turns out, successful fighters easily came in contact with people from the underground, as they met in the gyms and in the night life where many fighters worked as bouncers. In a friendly atmosphere, the risks of seduction were hard to recognize for inexperienced fighters.