Humor has been recognized as being important in promoting people's wellbeing and happiness. However, studies on the practical use of humor in the design process remain limited. The current work investigated the use of Giggle Popper, a set of principles for creating humorous products, as a conceptual model in the design process and examined its value for humorous product design by looking at case study projects. We observed how designers accomplished a design project involving the design of humorous water fountains using a software tool inspired by Giggle Popper. Three concepts from the Giggle Popper framework study were chosen for the investigation in order to evaluate the way in which designers developed three final prototypes: the Gas-Stove, the Hold-My-Hands, and the Slap-on-My-Face fountains. The findings suggest that Giggle Popper was helpful for improving and developing humorous products throughout the design process: including idea development, decision making, and implementation. Each principle was used interchangeably rather than independently, triggering the application of ideas derived from other principles. The principles of Giggle Popper were chosen and applied according to the characteristics of a product in order to create the proper context for humor. This paper demonstrated cases that showed how designers can use proposed design principles for real products. The findings of this study could help us to understand how designers and researchers use humor in the design process. The findings can contribute to practical design knowledge about how to create humorous products and can offer guidance on how to evoke positive emotions through products.