Someone asked this and I searched the archives but nothing.
This is in regards to nipples getting hard in the cold, and also during arousal.
Also (with regards to nipples becoming erect during cold exposure), why doesn’t the same happen to penile flesh?
I’m told nipples are “made of” (if that’s the right term) erectile tissue, same as penises ( I always want to say “peni”, but I digress). Difference is, nipples do not have a vascular setup which causes them to become engorged with blood when aroused.
But, I could be wrong.
It’s Nature’s way of attracting a man so the woman can bum his jacket. 
so, how does the erectile tissue work, if not getting engorged with blood?
They’re still “popping up.” :eek:
What we’re talking about is a hardening of the flesh in response to stimuli. To go back to the example of the penis, have you ever observed the changes in the flesh of testicles to weather, arousal, etc.? I think, again, that if not for the vascular setup in the penis that causes it to become engorged with blood so that an erection can be maintained through coitus, that the penis would also shrivel when aroused.
As to the “pop up” comment, I’d like to add that my nipples do not become larger when stimulated; they in fact shrink as the flesh tightens up. The reason people say that nipples “pop up” is that they now cause a “bump” in one’s clothing where there might have been a smooth line beforehand.
Ah ok, I see what you’re getting at.
Like if a man goes into cold water, his testicles shrivel up (not that I’ve seen this, I’ve just heard anecdotes 
).
Exactly! Or the way, just when a man ejaculates, his testicles get really small and hard in your han…oops, I think I may have crossed a line.
Elaine: “They shrink?”
Jerry: “Like a frightened turtle.”
Elaine: “I don’t know how you guys walk around with those things.”
We use correct termonology on SDMB. Testicles do not shrink in cold water but the scrotum and penis certainly do.
Nipples often harden because the woman they’re attached to sees me.
Isn’t “penises” the correct Latin plural of the word “penis” (meaning “tail”)?
I would only expect it to be “peni” if the singular were penus.
The correct Latin plural is penes. The correct English plural is penises.
Taking a break for the moment…hard nipples probably are easier for a nursing infant to latch onto and retain in the mouth…
But please carry on with the main conversation of the thread…
I would think the nipple phenomenon is more closely related to goose pimples than to the penis phenomenon.
Hmmm. I think there’s a Band Name in there somewhere.
In a related question, why do nipples get hard after peeing? It’s not sexually stimulating and not cold…
link.
Don’t know about nursing infants, but it works for me----