range of pain tolerance and scientific studies

I'm guessing there's not much known about the diversity of ball sensitivity/pain thresholds across the general population

probably would never get approved for research or grants from any mainstream institutions either

also seems challenging from a scientific standpoint:

* the only subjects likely to volunteer would probably have higher thresholds than normal, or at least experience a mix of pain and pleasure, so you'd get selection bias and not a representative/random sample
* reproducing the exact same sensations on multiple testicles seems difficult
* one options would be electrical stimulation via TENS unit
* maybe some sort of crusher with finely adjustable weight/pressure (vs how flat which is relative to original size)
* any sort of blunt force trauma would require building a specialized robot that can reproduce *exactly* the same movements at highly precise speeds