Is there a reason behind spontaneous nipple hard-ons? Lately one of my nipples just stays that way for the majority of the day. It's irritating! Is there a reason behind it?

1) I am a male with inverted nipples.

I was wondering if there is any way without surgery to make them come out. They do sometimes come out when it's cold, but go straight back in. I am not overweight, but I do no sports. Would physical activities help???

2) I have inverted nipples. Is there anything that I can do to make them come out? I think that they are unattractive inverted. I have tried massaging them daily as doctors and magazines have suggested, but they do not stay out. They have only come out a couple of times when my boyfriend has sucked on them. Is there something wrong with them? One doctor said that I might have to get a minor surgical procedure.