Why is it that blue balls hurt and how can they be avoided?

My take is ...: Blue balls syndrome is referred to ill-defined irritating feeling of "tension" or ache in testes or sac possibly related or resulting from poor prolonged course from sexual arousal to orgasm, first appeared in early 20th Century and first professionally discussed once in 2000. Its incidence and clinical subjective documentation have been santy. To me, it's a thing more psychological than physical.