Rules (fashion styles) of AltBoobWorld. See comments for brief list, but basically please don't be posing in underwear or lingerie, please don't be fully topless (must be clothing + boobs) and please don't clumsily roll up your top or pull it aside.
This one-boob top has a plunging off-the-shoulder line which has echoes of togas past while being a fashion that's modern and 'now' . Nipple jewelry is model's own.