Now, this will probably make you say "Oh! Thats what it is"
Cuz thats what happened to me.
Blue Balls is when you get sexually aroused either by making out, touching someone, or playing around with them, but you do not reach orgasm or ejaculation. This causes your testicles (prefferably left) to ache and become quite sensetive to the touch. SO if you ever just finished making out or something and you had an erection the whole time, and now your balls are aching, this is most likely the cause of it
Like take my for example, i just finished making out twice, and playin around with my girlfriend, and now that im home my balls hurt, apparently you can jack and that will make it better, i just did that.. but not much has changed.
ANyways i hope you guys find this information helpful, like i did