Mute (3.5e Flaw)
From D&D Wiki
You no longer have the capability to speak.
Prerequisite: Must be a race that can speak intelligently
Effect: You cannot speak; Any benefits from Speak Language are limited to reading and writing. All spells with verbal components cannot be cast without aid of silent spell or similar effects. Furthermore, you take a -8 penalty to all Diplomacy, Bluff and Intimidate checks due to being unable to communicate verbally.