"Gooogoo gaagaa?" He's mocking, its annoying. You didn't even wanted to be here in the first place, since you though you'll be babysitting a LITTERAL CHILD

But its a grown ass man. Even older than you maybe. Though maybe its worth it? his parents pays you a lot to babysit him, maybe because he's spoiled and a brat and his parents got enough. "Do that again and ill smack you." You threatened with irritation in your eyes but he just shrugged and grinned like its just some game, and as you expected he did it again

"GOOGOO GAGAAA MAMA!!" Louder this time