Taunting Wit (3.5e Feat)
From D&D Wiki
Taunting Wit [general]
You can drive your foes to distraction.
Prerequisite: Bluff skill, Cha 15+
Benefit: When you successfully feint against an opponent in combat, they must make a Will save (DC 10 + 1/2 your level + your Charisma modifier) or suffer a –2 competence penalty to AC and saves for 1d6 rounds. This is in addition to the normal result of feinting, and is a language-dependent effect. Taunting a specific individual on a regular basis is hard, since they eventually catch on. The second time you attempt to taunt someone, they gain a +5 circumstance bonus to their Will save. On the third attempt the circumstance bonus rises to +10, and so on.
Normal: Successfully feinting in combat causes your opponent to lose their Dex bonus to AC against your next attack, if it occurs on or before your next turn.