Relm: I couldn't miss the chance to practice my drawing!
This article is in need of a few pictures. Perhaps you can help by uploading a picture.
The Mimic glitch is a glitch in Final Fantasy VI which involves Gogo and his Mimic command. Unlike most other games, the Mimic command allows effects, such as those applied by magic or items, to be applied without consuming MP or using items; however, if Gil Toss is mimed, it will still use gil even though it should not.
The zero MP usage part may not actually be a glitch, but may be the way Mimic was intentionally designed, as Mimic behaved the same way regarding MP in Final Fantasy V. However, this is less likely regarding the issue with items not getting used up: in Final Fantasy V, the Mimic command actually did use up items, whereas in Final Fantasy VI, it does not, so this inconsistency is probably a mistake.