Much like the wilheim scream, it’s a popular stock sound effect. It’s in the intro of diddy kong racing, but it’s in all kinds of movies like Mulan, Monsters inc 2, Taken, the simpsons movie, Xmen 2, Gladiator. hot fuzz, wrath of the titan, resident evil the final chapter just to name a few.

actual stock sounds library it’s just called giggling 2 children soundideas.sourceaudio.com/track/11473800