Place it at the end of a brainy rant in your edit, right after the final point lands. Follow it with the galaxy brain meme sound to push the smart kid joke one level further, then cut to the reaction shot.
About this sound
This is a six-second spoken clip built around the line about a person who thinks all the time, delivered as a deadpan description of smart kids. It feels smug and teasing rather than mean, like calling out the friend who analyses everything before anyone else has even finished talking.