How to make nipples hard all the time?

i know this question is kinda weird but, i prefer having hard nipples all the time because it makes my pecs more defined and my pecs look good. My nipples are kind, how can i say this, are not nice looking when not hard, they're like bulging lips or a fat mountain...but when they are hard, they shrink and look better with my pecs...please help and give some advice...i always have to pinch them in public whenever i wear plain shirts to make them hard so they wouldnt be bulging out my shirt...it looks bad...