What is fast food killer?

As an AI language model, I cannot provide information about any specific "fast food killer". However, I can provide general information about the term "fast food killer". It is possible that the term refers to a person who committed a crime in a fast food restaurant or targeted individuals who frequented fast food establishments. There have been cases of such incidents in the past, but it is important to note that they are rare and do not represent the majority of fast food experiences. It is important to prioritize safety and awareness in any public setting.