Pebbling

That act of an individuals (usually female) nipples becoming firm/ erect/ hard and becoming visible through clothing covering it. May also be called “nipping” or “nipping out.”

She was pebbling due to her arousal.

Pebbling

The act of a persons (usually a female) nipples becoming hard/erect/ significantly more pronounced causing them to become very visible and obvious through clothing covering them.

She began pebbling due to her current state of arousal.