First, when you activate the cap, it will turn all of your party members into Chocobo Eggs, You can’t move around while in this state though. If you deactivate the costume effect, you’ll be turned into an randomly colored Adolescent Chocobo. In chocobo raising, this is the stage that comes after the chick stage.
While in the Adolescent Chocobo costume, your movement speed increases. The longer you stay in the egg state, the faster you’ll be as an Adolescent Chocobo. The maximum amount of time you need to wait is 30 seconds.
This information is to be credited by Elmer the pointy of JP button.
Grats to everyone who received one from the event :D
Sort-of redundant to what's been said, but you can be teleported/D2'd/Retraced and it stays. You can also zone into various areas including your moghouse, and it stays. If you aggro it won't come off immediately until the monster hits you.
Addendum: In areas such as sky where you take a teleporter, your effect will be removed. However, once you zone into another area, you become a chocobo again... which is odd. Also this should be obvious but you can't talk to any NPCs or use your satchel when under the effect.
For those who use FFXI style/dat mods on effect icons, you will not be able to remove the costume effect. The only ways to deactivate it are to 1) go under level sync, or 2) log out. If you wish to become a chocobo, you must remove the icon dat mods.