Very Happy Kids

A prank with peaceful music showing smiling and laughing happy babies. However, in the last clip of the video, a a man's voice saying "Make a scary face!" is heard. Then, the baby's face suddenly turns into a scary monster face with a loud scream in the background. After a few seconds the face goes back to normal.

Links
NOTE : The following video contains a screamer.
 * youtube.com/watch?v=UDwIS55qX2Y