n: the small bumps that form on top of the shoulders of shirts (typically men's, but not exclusively) after they have been hung on clothes hangers.
"I wanted t wear this shirt today, but when I took it out of the closet it had shoulder nipples on it."
When you dry/hang your shirt on a wire hanger and the hanger causes the fabric to stretch out and creates a small imprint resembling a nipple on each shoulder.
That chick be sportin' shoulder nipples! That beezy best be gettin' some padded shoulders beetch!
Bitch, best start neatly foldin' yo laundre.