The Tapir bug in Final Fantasy VI involves the Tapir Dance.
Tapir removes Darkness, Zombie, Poison, Imp, Petrify, Doom, Silence, Berserk, Confuse, Sap, Sleep, Slow, and Stop. Unless the player watched closely or knew how it worked, the only time they would see Tapir hit is when a character had the Sleep status. In reality, it removes all the aforementioned ailments, but the game registers a Miss message anyway unless that character has the Sleep status.
The reason is that the special effect in Tapir forces the game to produce a Miss message whenever the target in question is not under Sleep status. When they are, the game will not give the Miss message and will restore full HP and MP to the character under the Sleep status, even if the target is undead.