I know this is quite the necro, but I think it might be worth it.
Basically, I commissioned a nipple expansion animation not too long ago, and I realized now that this would be a great place to show it off.
It's of Nami from One Piece, who experiences a sudden bout of breast expansion. No sooner is it over before her nipples swell up to match her new boobs, then keep right on going.
Nami Breast/Nipple Expansion Animation