From Testicular volume is inversely correlated with nurturing-related brain activity in human fathers in PNAS:

One participant’s testes volume measurement was excluded because his value was 2.8 SDs above the mean (mean = 38,064; SD = 11,183) and was more than 13,000 mm^3 larger than any recorded value found in the literature. Of the more than 1,500 healthy, age-matched men in these studies, the largest reported value was 56,000 mm^3, and this participant’s measurement was 69,736 mm^3.