I am an exhibitionist, and I love embarrassing people by 'accidentally' letting my nipples become exposed. I do this most when there is no chance of meeting anyone I know, such as when I am on holiday or on public transport; it also helps if I pretend to be asleep, so people can't really say anything...
I have medium-sized breasts, with quite large pink nipples. When I want to make them seen, I normally wear a strapless top that I casually let slip under my nipples. If I'm feeling really brave, I'll walk down the street this way with shades on.
When I know I will be in a position to lean down, I wear a loose top that will fall below my breasts. If I'm wearing something tight, I put hairpins around my nipples to make them protrude as much as possible.
In changing rooms I often parade naked, and once even paraded with pegs on my nipples as though everything was normal. In public bathrooms I sometimes spill water on myself on purpose to give me an excuse to change my bra. Sometimes I 'forget' my bra and find I'm wearing a translucent blouse.
When I go to the beach topless, I paint my nipples bright red with body paint..
The other day I clipped hair clips onto my nipples over my blouse and did my shopping this way.
Tomorrow I have a trip to the sauna planned and I fully intend to rub oil and honey onto my nipples as though they're meant for nothing else...