Okay, as an example, in vanilla Fallout, you take the Rock-It Launcher, aim it at some guy, it shoots too low, and beans him in the walnuts. Nothing happens except he takes damage and maybe a leg gets crippled in the process.
Now, imagine you have a Nutshot Mod enabled, and you take the Rock-It Launcher, aim it at some guy, it shoots too low AGAIN, and beans him in the walnuts like before. Except this time, he grabs his crotch, keels over, and moans in pain for a good 5 to 10 seconds. Would give you a tad bit of an advantage in combat, but in my opinion, it would also be pretty funny. (Only because the guy would be trying to kill you, though.) It would also add a bit to the realism, too. I mean, what person could get hit in the walnuts with a two-pound TOASTER at high velocity and not keel over in pain? (And if you say chuck norris, I will hunt you down and beat you to death myself. I'm REALLY tired of all the chuck norris jokes i've been hearing.)
Anyways, Nutshot mod, anyone willing to do it? I would do it myself, but I don't know left from right as far as creating mods go. (It would also have to be scripted for human males only, unless you want Ghouls (which have no visible reproductive organs, if you count the wild ones), and women to keel over in pain.
Women having male reproductive organs would be understandable to some extent, unless ALL the women had it, which in that case would just be absurd, considering the factor that quite possibly only a specific niche in the genepool of women would become hermaphroditic/gender changed because of radiation exposure.
Anyways, just throwing the idea out there, incase anyone with a good sense of humor feels the need to give us Fallout players a reason to "Ode to Nutshot" a couple hundred raiders or so.
Doesn't radiation make you sterile? Might that maybe take away from the pain some?
Also, it hurts like hell there even if you're female. Entirely off subject, if you see an annoying feminist talking about how her body is better than any mans and get the urge to kick her there for a good laugh, DON'T.
Incidentally, if this mod ever pulls through, I would like to patent my idea for a "Balls of steel" perk.

Seriously though, this probably won't happen. Too much work for such a small thing.
And, as a piece of advice, don't go around the internet saying "Don't post such and such" unless you want to get trolled.