It has been 50 years since the biohazard warning trefoil was innovated. Inspired by but differing from the radiation warning trefoil created in 1946, each of these symbols, in the appropriate context, instills a sense of dread and doom to all who are near. Nobody desires to handle without extreme caution that which would cause them extreme harm. This is the case even though very few of us have had direct experience with the consequences of mishandling hazardous material. This talk is a call-to-arms. It is high time that we begin treating our soon-to-be terrifyingly-intelligent mechanical brethren with the same respect. During the last few decades warning symbols have become emblems of popular culture. In most instances of popular use, warning symbols are taken entirely out of context in a haphazard revelry of symbology misuse. We seem to delight in the dramatic juxtaposition of dire warnings in mundane contexts. The radiation trefoil on the computer laptop or the bedroom door of a teenager tells a very different story from the same symbol on a metallic canister in a research laboratory. This popularization and misuse is one of many reasons that we believe cyber threats demand their own warning symbol. Deadly software and infected hardware need uniquely identifiable markings. We believe that consistency and widespread adoption are key. It is insufficient to attempt reuse of traditional warning labels. The consequences of handling hazardous computational materials with insufficient or ambiguous labeling could be dire. In this talk we discuss the cultural, psychological, and practical basis of warning symbols and techniques to bring these ideas to bear on labeling and handling of malicious code and devices. We then present a set of prototype “trefoil” warning icons and discuss approaches for labeling, identifying, and safe handling of malicious material.