"Insult"? :D

[Peter_20]

Wow, how the hell does this Ability work?
Haha, gotta be one of the funnier things ever invented in the FF series.

Obviously, according to this site it's supposed to work like "drive enemies insane with insults",
and that sounds pretty hilarious.

[Despotus]

yep, basically. You drive the enemy into a rage by insulting them until they reach the 'Berserk' status, where an enemy will only attack you with their basic physical attack. Pretty useful in my opinion, especially against enemies like the Vampires, Red Chocobos, Mind Flares, Apandas, Tiamats, mages, etc. that have nasty special attacks.

If you're asking how it works, you can use 'Talk Skill' on any human; but you must be a Mediator or have 'Monster Talk' equipped to use it on monsters.