Place it after the line you want to mock in your edit, then follow it with Auughhh as the reaction beat or Chipi Chipi Chapa Chapa as the closing sequence for a group montage.
About this sound
This is a 10-second clip of high, baby-like babbling that strings together goo goo gaga sounds and nonsense thuknana syllables in a repeated, sing-song run. It feels gleefully silly and a bit bewildered, like someone has completely given up on real words and is happily talking in pure infant gibberish instead.