Short Temper (3.5e Flaw)
From D&D Wiki
You get enraged easily, going berserk whenever you suffer damage.
Effect: Whenever you suffer damage, you become enraged. Whilst enraged, you take a -2 penalty to Armor Class and cannot make Intelligence, Wisdom or Charisma-based skill checks. You will stay in this enraged state for 1d4 rounds or until the thing that caused them damage is defeated.
Special: Even if you take damage while in this state, or have taken damage from multiple sources, the original target remains the focus of your rage until the duration expires. Once the duration expires or the original target is killed, this flaw can be triggered again.