shadow caster 

An erect (usually female) nipple that protrudes through clothing enough to cast a shadow in full light.

Dude, check out the shadow casters on that chick's fun bags!

shadow caster by un_malpaso March 13, 2009

shadow caster 

A pest, a nuisance, someone who follows you around constantly, but poses no danger like a stalker.

That guy is such a shadow caster. Every time I turn around, there he is...all up in my face.

shadow caster by Anonymous June 20, 2003

Shadowcaster 

Noun: An involuntary erection whilst sitting fully clothed capable of casting a noticable shadow on the torso of the offender.

Having beers around the fire one night Quinton popped an absolutely absurd Shadowcaster.

Shadowcaster by Alcatrazz69 October 31, 2012