Place it immediately after the reveal that makes age the surprise, then follow with Bruh or 67 Kid Meme to extend the reaction, keeping the age joke as the centre of the edit.
Об этом звуке
This is a short Dutch voice clip saying 'Hij is nog maar 17', meaning he is only seventeen, delivered in a flat, matter-of-fact tone in under two seconds. It lands as a dry, slightly teasing remark, the kind of line that makes a bold claim or a grown-up moment feel suddenly much younger. Its bluntness is what makes it funny in a reaction.