Geronimo!

Geronimo!

An exclamation of excitement, typically used when one does something daring, especially jumping from a height. Jake peered out the open door of the airplane and yelled "Geronimo!" as he leapt out.
Farlex Dictionary of Idioms.

Geronimo!

(dʒəˈrɑnəmo)
exclam. Here I go! (Originally said by parachutists leaving a plane. From Spanish for Jerome.) There’s my cue. Geronimo!
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • boom goes the dynamite
  • dynamite
  • hoo-rah
  • gotcha
  • schwing
  • Schwing!
  • ah
  • viola
  • voilà
  • Woe is me!
References in periodicals archive
"Words aren't enough to describe how proud I am right now, how proud I am of The Sarah Geronimo!! She really is the best representative of the Philippines in events like this!
WATCH: Sarah Geronimo sings Filipino songs at international music fest
Of course, the night wouldn't be complete without the band singing their number one hit "Geronimo." Everyone jumped and danced as they sang along to the song's catchphrase "Say Geronimo!"
Sheppard: Full slice of soulful pop
While leading a charge against Mexicans they began to shout 'Geronimo!' seeking help from their patron saint, Jerome, or Geronimo in Spanish.
Geronimo