Can you get Blue Balls just from being involuntarily hard?

Semen starts being created as your penis receives stimulation. As long as you have hit puberty, each time you have an erection, consciously or unconsciously, semen is being produced in your testicles. When you get stimulated or "edge but withhold climaxing", and dont release the semen build up, your testicles become sore from the pressure and extra bloodflow. Which would explain the "blue balls" feeling.

 

I have experienced this personally as well. I'm currently on day 17 of Nopmo, and the days that I had been exceptionally more horny, I soon after experienced a dull ache.