Objectives Pre-prepared smiley face symbols are used widely to gather information on, for example, satisfaction with services or health and well-being. We investigated how women and men of different ages respond when asked to draw a smiley face for themselves. Our objectives were to investigate how they differ by generating a unique set of data to explore this simple human behaviour and to illustrate the importance of considering gender and age mix in any study. Results We collected 723 drawings, in a variety of settings. Gender and age were provided for 676 drawings (women: 511; men: 165; ≤ 30 years: 335; > 30 years: 341). Although similar proportions of women and men drew some features, such as closed mouths; women and those aged ≤ 30 were less likely to draw noses and outlines around the faces, and more likely to draw a classic smiley face. Our analyses provide a novel way to highlight that whenever self-reported outcomes are compared between groups, the group composition for characteristics such as gender and age may need to be considered carefully to explore whether differences in outcomes might simply arise from imbalances in those characteristics.