It's probably true that "blue balls" comes from a congestion of blood in the testicles. For a while I thought it was a backup of semen, but I have on occasion dropped my Kleenex while masturbating and, to prevent a mess, squeezed my penis shut at orgasm time. If a sperm backup caused blue balls, I surely would have suffered then. With that out of the way, let me get on with my blue ball experience:
First, some background. I'm a male, 42 years old and in mediocre physical shape: it would probably take Viagra to move enough blood into my nether regions to give me blue balls these days. Thus, I can't even remember when I last suffered from this problem; but I remember well one of the first times I did. Here, just to set the atmosphere for my readers with testicles and perhaps as an eye opener for those without, is a testicular summary (a testimony, if you will) of what more cerebral individuals would politely describe as "a romantic evening":
she's kinda cute and it's real gratifying that she feels comfortable enough around me to follow me up to my dorm but is she making fun of me now in the hall by the phone taking her comb to my scant chest hair and giggling all the while but what the heck she's the only girl around and she's probably just kidding and besides if she's interested in my chest hair maybe she's interested in other aspects of my masculinity which we'd better explore inside my room so come on inside hanging on my arm she probably wants to smooch right now and has a cute giggle that turns me on as I reach for her a little more boldly for a few teasing pecks before we talk and laugh together some more and we're getting along real fine so to hell with this and let's see if she'll let me kiss her a lot more seriously better get a good grip on her and lean her against the wall because ooh yes she likes to use her tongue too hmm that's nice come on little girl let's slide on down on my bed since we're wearing clothes it's all right now I can get even closer to her legs wrapped around mine and so is her tongue giggling even her earlobe tastes good and her hair feels nice across my face while I try to suck the life out of her mouth I get a real firm grip on her ass in those nice tight jeans and her body is feeling so warm against mine her hands are leaving little electric spark trails where she touches me and her little breasts are squeezing against my chest where my shirt is open so I feel more and she's snuggled up so nicely against my body that I'd really like to see and feel her naked and I wonder if she'd mind if I undid her
Hey! *giggle* Stay out of there! I've got to go home, I'll bet my mother's wondering what's taking me so long at the Computer Science Center.
Umm... yeah, I guess you're right. Lemme pull myself together, I'll walk you to your car.
So at this point we'd been making out pretty heavily (I thought so, anyway) for about two hours. I not only lusted for her (I lusted for almost anything female on two legs, those days) but genuinely liked her too. It'd been months since I'd been in a situation anywhere similar. I was strongly excited, sported an obvious tent in my pants and had a strong urge to progress to sex.
Why are you grimacing like that?
Umm... well... my balls hurt! I think it's called "blue balls".
Oh. Poor boy! *giggle* I had no idea! Maybe we shouldn't have...
No, I'm very glad we met and I thoroughly enjoyed myself. I hope we can do it again soon. The pain's not bad, it'll go away and when I come back from the parking lot I'll go to bed thinking pleasant thoughts about you.
So, with the objectivity of 20 years of hindsight, let me recapitulate: Blue balls don't happen all that often, at least to me, but there definitely is physical pain. I've thought hard about how to describe it, and I'd say it's comparable to a headache in the early stages. The kind of headache that people manage to work through if they have to but that definitely impacts their well-being. The kind of headache that sends many people scrambling for their Aspirin for fear of having it last any length of time or, heaven forbid, getting worse yet.
As I remember it, the pain stayed with me for about an hour, leaving a lesser but lingering pain after-image that lasted until I managed to get to sleep. Of course I was fine the next day.
And yes, the guilt thing worked on her, and I remember getting many pleasant hand jobs from her, as a substitute for sex, which she steadfastly refused. But really, I hadn't told her about my "problem" to make her guilty, I was just being honest. She, on the other hand, enjoyed the intense effect she was able to achieve on me with a simple light motion of her hand, and that it kept me absolutely addicted to her. And as long as we dated, she never let me get blue balls again.