I'm not sure whether this is a lucky ship or a lucky chick image that the chick was given to the one girl that wasn't going to break the egg... (Of course, this is a "nicer" series, so I hope we don't see any "Yukikaze the reaper" references after this...)
*shatter*d'aww*roll*Today is Egg day.*SLAM*It is called the Columbus Day in the United States.
See also its Wikipedia page.
It is also called the Discovery Day in the Bahamas. (Columbus found the island Guanahani, inside The Bahamas.)
The girls are trying to stand an egg on its end, which is an apocryphal story about Columbus. The answer is to break the egg, like Ushio does.
*CRACK**roll*October 12thHii-yammander!!She shouts "chiree!", which is notably similar to her "shiree" she calls the admiral/commander.
