Place it at the start of a fake alert sequence, then follow with a smoke detector beep for a second false warning before the reveal. For a stronger follow-up, put a shocked meme sound right after it, and save the FNAF 2 jumpscare scream for the final cut when the prank is revealed.
About this sound
This is a short, high-pitched beep modelled on the emergency alert tone an iPhone plays for an EAS warning. It lasts under half a second and arrives as a single sharp chirp, with no build-up or longer alarm pattern behind it. The effect is abrupt and startling, like a real phone warning cutting through a quiet moment, which makes it work as a sudden interruption in a joke.