First off are you talking about touching your breasts or masturbation when you say "stimulate ourselves." If your talking about touching your breasts, yes they will get hard, if your talking about masturbation, they could or they could not its kind of a case by case senario. In regards to the normal color of nips, every person is different. Nipples can very from a very light pink, just slightly darker than your natural skin tone, to a rather darker pink.