The animal with the biggest testicles is an insect!
It is the coastal deciselle or Platycleis affinis that holds this record. This species of grasshopper has, in fact, the largest testicles of the animal kingdom. The genital glands of this grasshopper represent 14% of its body weight. To put this in perspective, the testicles of a man weighing 80 kilograms with this ratio testicular mass / body mass should weigh 11.2 kilograms.