It's Showtime!

A Stock Phrase and a specific instance of Pre-Ass-Kicking One-Liner, "It's showtime" (or just "Showtime") is used often enough in media to count as a trope on its own. Its utterance by a character usually heralds the time to get dangerous, or the moment when a deception or disguise is about to be critically tested.

Naturally, this trope excludes instances where someone is announcing that an actual performance is about to start.

Not to be confused with the Philippine noontime variety show of the same name.

Anime and Manga

 * Roger Smith summons his Humongous Mecha The Big O by activating his remote-control watch and bellowing "Big O! Showtime!"
 * Late in the series, when Alex Rosewater activates his mecha, he calls out "Big Fau! Showtime!"

Fan Works

 * The first time metahuman Douglas Sangnoir goes into battle at the side of the Knight Sabers in Drunkard's Walk II, he declares "It's showtime!" to himself.

Film

 * When Lydia Dietz finally invokes him at the climax of Beetlejuice, Betelguese looks up from the miniature headstone on which he's been sitting, grins, and growls, "It's showtime."
 * Matt LeBlanc as Major Don West in the 1998 Lost in Space movie declares "Showtime" when it comes time to launch the Jupiter II.
 * Bob "Mr. Incredible" Parr says "Showtime" at multiple points in The Incredibles, always just before launching into superheroics.

Video Games

 * in Marvel vs. Capcom 3: Fate of Two Worlds, the Black Cat declares "Showtime!" to the consternation of Spider-Man, who claims it as his line.