Steroids shrink testicles, but only slightly. Since steroids add more testosterone to your body, your brain signals your testicles to cut down on the testosterone production, because there's too much present in the body. Due to that, testicles will shrink by a small amount, because there is less testosterone stored there.
The more you know.
As for the shark semen making testicles larger ... I found nothing via google. Someone just wanted his friend to drink a glass of semen.
