Through protracted self-mutilation that involves frequently piercing your tongue and dipping it in acid, your tongue becomes hideous to behold but oddly sensitive to the environment.
Prerequisites: Evil alignment, Willing Deformity.
Benefit: You gain the ability to sense your surroundings by taste, much as a serpent can. You gain the blindsense ability out to a range of 30 feet.
Source: Heroes of Horror, page 121.