It's nice that someone else bumped this thread other than myself!
My wife has been wearing REALLY thin pjs lately and staying braless around others if they stop by. She knows her flat nipples and areola are perfectly outlined, but since they are long-sleeved and up to her neck, she doesn't understand what is so exciting about them.
Her best friend (female) stayed the night the other night and didn't break eye contact with my wife's nips the entire time. Ha! I didn't blame her.
Her friend also wore pj's without a bra that revealed a lot, also with all of her skin covered, but they were so form fitting that you could make out her inverted nipples perfectly.
That was a great night for me, for sure!