They are always visible.
Even when clothed.
Even when denied.
Even when you pretend they are irrelevant.
Nipples are the first to react, the last to forget, and the most dangerously honest part of your body. You can hold back your words. You can modulate your tone. You can slow your breath. But your nipples?They betray you. Every time.
And that is precisely why they must be trained.