Countdown

Countdown is a screamer video uploaded to YouTube on April 27th, 2009 by Steven Anderson, in which the timer was set at 60 seconds.

Video
The video starts in 60 seconds of the timer. After 30 seconds had passed, the theme song from the American gameshow called ''[https://en.wikipedia.org/wiki/Jeopardy! Jeopardy]'' plays. When the timer runs out flashing, the buzzing alarm plays for 2 seconds, then a picture of Regan MacNeil from The Exorcist pops up along with the girl screaming. The screamer itself is not scary at all as the screaming sound is generic and it isn't so loud (which makes your ear gonna bleed.)

Link
NOTE : The following video contains a screamer!
 * youtube.com/watch?v=9-N2N9QquSM