Joking about nipples is not done. I love to rub vodka on them to get them more sensitive. If you want to know more I might make a post in Real Kinky.
I like to tweak my nipples,as a substitute for bashing the bishop,it shifts my attention towards an invigorating slight pain.
The x chromosome. Men are half female, women are all female. Extra nips mean that the person is a werewolf.
I've never understood this debate. Its like "why do women have clitorises". (Which ok, some guys think "yeah why do women have them..." :- / ) But seriously, they do have a major use. Its a shame when women don't really understand how they work IMO.