Pebbling

[GarryDrold]

when the [areolae] on breasts begin to become aroused, they often get [goose bumps] which makes them look like they are covered in [pebbles] as they start to harden and tighten.

[Justin Bieber]

The action of treating leather with a roller to produce a rough or indented surface, as if impressed by pebbles; the pattern itself. Also in extended use: a similar texture or pattern on other surfaces.