Earplug

From Final Fantasy Wiki

Earplug, also known as Finger Guard, is a reaction ability in Final Fantasy Tactics. The Orator class learns it for 300 JP. Whenever an enemy unit tries to use a Speechcraft on a unit with this ability, there is a chance that the Speechcraft will fail.

v · e · dFinal Fantasy Tactics Abilities
Squire	Fundaments - Counter Tackle - Equip Axes - Beastmaster - Defend - JP Boost - Move +1
Chemist	Item - Auto Potion - Throw Items - Safeguard - Reequip - Treasure Hunter
Knight	Arts of War - Parry - Equip Swords - Equip Shield - Equip Heavy Armor
Archer	Aim - Adrenaline Rush - Archer's Bane - Equip Crossbows - Concentration - Jump +1
White Mage	White Magic - Regenerate - Arcane Defense
Black Mage	Black Magic - Magick Counter - Arcane Strength
Monk	Martial Arts - Critical: Recover HP - Counter - First Strike - Brawler - Lifefont
Thief	Steal - Vigilance - Gil Snapper - Sticky Fingers - Poach - Move +2 - Jump +2
Mystic	Mystic Arts - Absorb MP - Defense Boost - Ignore Weather - Manafont
Time Mage	Time Magic - Critical: Quick - Mana Shield - Swiftness - Teleport - Levitate
Geomancer	Terrain - Nature's Wrath - Attack Boost - Ignore Terrain - Lava Walking
Dragoon	Jump - Dragonheart - Equip Spear - Ignore Elevation
Orator	Speechcraft - Earplug - Equip Gun - Tame - Beast Tongue
Summoner	Summon Magic - Critical: Recover MP - Halve MP
Samurai	Iaido - Bonecrusher - Shirahadori - Equip Katana - Doublehand - Swim
Ninja	Throw - Vanish - Reflexes - Two Swords - Move in Water
Arithmetician	Arithmeticks - Cup of Life - Soulbind - EXP Boost - Accrue EXP - Accrue JP
Dancer	Dance - Fury - Bravery Boost - Jump +3 - Fly
Bard	Sing - Magick Boost - Faith Boost - Move +3 - Fly
Dark Knight	Darkness - Max HP Up - Vehemence - Move +3/Jump +3