There's a good chance that you could have Wandering Nipple Syndrome.  This is a condition which permits your nipples to have autonomous control, meaning they can get into all sorts of scrapes... with hilarious consequences!  It is a genetic disorder, harking back to an earlier time in our evolution, when nipples served as rudimentary feelers.  They react to light, so the best course of action would be to keep them subdued beneath a dark vest whenever possible.