This paper describes a study conducted in collaboration with a marketing agency and a nonprofit organization (NPO) providing regional sexual health services, which included advice on, and testing for, sexually transmitted infections (STIs). The study investigated the relative effectiveness of different formulations of double entendres on appeal, humor, the likelihood of social media engagement, and intention to seek more information about STIs. Advertisements containing double entendres were significantly more appealing and humorous if: (1) the grammatical formulation did not cue the intended meaning; (2) the double entendre involved a creative metaphorical expression; and (3) the double entendre referred to the middle part of the sexual scenario, referring to action rather than intent or result. Participants' ratings varied very little according to their age, gender, and education. However, a qualitative investigation of the free-text responses revealed that there was some variation in the types of interpretations that were offered by participants depending on their age, gender, and education. The marketing agency incorporated our findings into their live campaign, which resulted in a notable increase in: (a) website traffic and social media engagement; (b) STI home-testing kits ordered; and (c) STI kits returned for testing, compared with previous campaigns.