Booyah!

Booyah! is a signal in Splatoon and Splatoon 2.

Usage
There is no agreed-upon usage in the playerbase, but it is presumably meant to indicate to one's teammates a (combat?) victory.

In the watered-down European localization, the signal reads "Nice!", which has a broader and different use entirely.

The Booyah! signal is spammed a lot, especially in squid parties, or after an Inkling has been splatted. The latter is somewhat useful as it allows for the tracking of splatted teammates. (C'mon! will not work before respawning as it is literally translated as "To me!", which could lead to the demise of teammates responding to the signal.)

Trivia

 * To be fair, in The Emperor's New Groove he did shout "Booyah!" as he was going over the waterfall.

Name origin
The name may be a reference to the Booyah Base, a shopping district in Inkopolis Plaza. Were this true, it would also be a pun on the word "bouillabaisse", a Provençal seafood stew including clams, lobster and other fish. This is mere speculation, however.

Names in other languages

 * German: Cool
 * Italian: Grande! Great
 * Japanese: ナイス Nice
 * Spanish: ¡Genial! Great