This case study focuses on the example of Mr. Yuk, a character used primarily in the United States to educate children in the prevention of poisoning. In its extreme stylistic simplification, Mr. Yuk bears a strong resemblance to the underlying design principles of contemporary emoji, although he made his appearance as a material sticker prior to the launch of emoji. Mr. Yuk was first introduced as a registered trademark in 1971. Even the simplest character designs, like those of the Mr. Yuk stickers, seem to be able to display a specific emotion, despite their plain structures. However, Mr. Yuk was not only meant to function as the personification of the basic emotion of disgust, but he additionally came to replace the common ‘skull and crossbones’ pictogram as a general poison warning, a much older and internationally standardized warning sign. This chapter sets out to explore the design considerations and their underlying assumptions for the alternative warning sign of Mr. Yuk—developed with regard to the specific target group of toddlers and children. Thus, at the center of interest lies an evaluation of the results of experiments dealing with the effectiveness of Mr. Yuk. The contribution will finally try to answer the question of whether or not the addition of facial expressions can help to simplify the interpretation of pictograms and thus increase their efficiency. Findings of facial expression research, for example, the ‘Facial Action Coding System’ developed by Paul Ekman and Wallace V. Friesen, are used to clarify whether Mr. Yuk can be considered a successful representation of the facial expression of disgust and in how far it can be considered ‘universally’ comprehensible. Finally, this examination also touches on some implications involved in the understanding of contemporary emoji.