Place it as the instant reply after the annoying line in your edit, then follow it with the awkward moment sound to let the reaction hang. If you want a cleaner version for younger viewers, swap in the dolphin censor sound instead of the swear.
About this sound
An almost three-second voice clip of Himemori Luna snapping the line STFU A-hole in a sharp, blunt delivery. It feels instantly rude, funny and dismissive, like a cute anime voice suddenly dropping all politeness to end an argument on the spot. The contrast between her sweet tone and the swear makes it land as a comedic shut-down.