Why do my testicles hurt if i don't have sex? is this "blue balls" ? yes this is a serious questiion.

"Blue balls": The condition you describe is most often due to prolonged erection. The erect penis, although engorged with blood, actually has ver low blood flow in and out . This "ischemia" due to poor oxygen delivery to the penis tissue eventually causes severe penile pain which often is referred to the scrotum and testes. Ejaculation typically causes the erection to subside. Thus, blood flow improves.

Likely mechanism: Dr. K is correct about the phenomenon though the "traditional" mechanism about vessels dilating and constricting seems as unlikely as archaic discussion of migraine. During prolonged arousal, enormous amounts of fluid accumulate in the seminal vesicles and this must press on the genitofemoral nerve producing referred pain, since the copious emission instantly ends "blue balls".