Place it at the exact cut where your character first appears, then follow the reveal with a FNAF jumpscare scream if the mood turns hostile, or a Roblox oof when the flower's plan immediately backfires on you.
About this sound
A 2.6-second voice clip says 'It's me, Flowey' in a bright, playful character voice. It feels cheerfully unsettling, friendly on the surface with a hint that something is off. The line references Flowey the Flower, the deceptive character who introduces himself early in Undertale, the 2015 role-playing game by Toby Fox.