A portion of one's shirt that is exposed when one forgets to zip up their pants. The term is used in at least one "Simpsons" episode by the character named Nelson.
by John and Alan Moore December 28, 2007
when part of one's shirt has been zipped into the top of one's pants zipper, and thus the tip of the shirt sticks out of the zipper, like a penis, but made of shirt material.
Felix got dressed in such a rush that he didn't realize he had a shirt wiener; he didn't get the job.
by CandyLandy December 2, 2009