When someone wears a button down shirt tucked in and they forget to do the last button, thus revealing a triangular shape of skin showing off his/her happy trail.
Man 1: Hey look Daves triangletrail is out again
Man 2: Ew, I swear he could briad all that hair if he really tried.
Man 2: Ew, I swear he could briad all that hair if he really tried.
by sillimilli5 April 4, 2011
Get the Triangletrailmug.