Objectives: To evaluate whether blondes have more fun, as proposed by Sir Roderick David Stewart in 1978. Design: Prospective, non-randomised crossover field study, 1–2 June 2018. Setting: Single centre medical writing course, during a break in the course program. Participants: Convenience sample of 21 healthy Danish researchers: ten blondes, nine non-blondes, and two with missing data (bald). Intervention: Participants completed a visual analogue scale (VAS) for fun and Profile of Mood States – Adolescents (POMS-A) questionnaires before and after two rides each on a waterslide (once sitting upright, once lying down). There was a wash-out between rides. Main outcome measures: Fun, as assessed by VAS completed moments after completing each waterslide ride. Results: Blondes did not have more fun than non-blondes, neither while sitting upright (median VAS, 60 [IQR, 23–66] v 25 [IQR, 4.5–57]; P = 0.39) nor lying down (median VAS, 70 [IQR, 60–85] v 66 [IQR, 35–80]; P = 0.62). Riding the waterslide lying down was significantly faster (median duration, 9 s; range, 8–13 s) than sitting upright (median duration, 13.6 s; range, 8–37 s; P < 0.001), and also more fun (median VAS, 72 [IQR, 59–85] v 41 [IQR, 14–66]; P = 0.002). Conclusions: Our findings are not consistent with the statement by Sir Roderick David Stewart that “blondes have more fun”; we found no evidence that blondes experience more fun or are more susceptible to mood changes than non-blondes.