Yes. "Blue balls," are caused because of vasocongestion in the sex organs. You know that in order for a man to have an erection more blood has to go into the penis than out of it. What you might not know is that to effect ejaculation, all the ancillary organs like the vas defrens, prostate, seminal vesicles, epididymus, and testes all have to work together and work quickly
to mix the semen together and get it to the base of the penis to make it all happen.
Mix it all together? Like a plumbers epoxy? 
All that requires the organs to work hard and to make organs work overtime, you need a lot of oxygen and a lot of blood to supply that oxygen.
Ever notice that a man's testes swell to twice their regular size just before ejaculation? They do and they're working hard!
I have noticed they get high and tight with most men; but honestly hadn't noticed a doubling in size.
I will next time though. :wink:
When a man ejaculates, his body releases prolactin which tells the blood vessels in the area to stop blocking flow and also tells all the organs of the body to stop working so hard. It also tells the brain that sex is over. Just. Like. That.
This is why men are so disinterested in sex (usually) immediately after ejaculation. The lowest point of a man's sex drive is immediately following ejaculation and it's entirely because he's releasing a hormone that virtually shouts in his ear, "STOP CARING ABOUT SEX!!! WHAT'S IN THE 'FRIDGE??"
tee hee hee :wink: Cute explanation, but I still want some cuddling post-coitus.
Blue balls occur because prolactin doesn't get released even though arousal has ceased. As a result, all the organs haven't received the official word that sex isn't about to happen. They keep working to an end that will never (ahem) come. This causes blood to pool in the organs of the groin and particularly the super-sensitive and nearly doubly-sized balls. This causes throbbing and soreness that is very real and occasionally truly painful.
The best thing for a man to do is just to jack-off. If this is impossible due to circumstance, then the next best thing to do is wait or pop a Benadryl. The aching usually subsides within half an hour or less.
Okay, I swear I was paying, but I don't get how Benadryl helps, it's an anti-histamine. Does it stop the flow of prolactin?