Place it as the reaction shot after a character does something foolish, then follow with the Awkward Moment sound to stretch the beat, and use the Eh Eh Ehhhh sound beforehand when you want the setup to build before the question lands.
About this sound
This is a short Japanese spoken line, lasting about two seconds, in which a voice asks 'What are you doing?' in a direct, questioning tone. It lands as confused and confrontational, the kind of blunt reaction that calls out strange behaviour in the moment.