noun - an extended soulpatch. A long vertical strip of facial hair directly below the lower lip, beneficial for stimulating the taint during cunningulis or salad tossing.
A taintbrush is when someone walks around on a hot summer day, saturating the taint and its hairs with sweat. Once saturated, it is then used to paint on a sleeping person's forehead.
My roommate used his taintbrush on his sleeping girlfriend and blinded her by getting sweat in her eyes!