Place it at the very start of the edit, right as the younger person appears, then follow it with a Bruh sound for the deadpan reply and a baby laughing clip for the next reaction.
O tym dźwięku
The clip is a very short spoken greeting, lasting just under two seconds, in which a voice says 'Hi young boy' in a direct address. It feels light, playful and a little cheeky, like a quick hello meant to catch someone's attention and make them smile. That brief, friendly tone makes it easy to recognise and reuse as a reaction.