Shock.swf

Shock.swf is a screamer animation prank created by the prestigious Massachusetts Institute of Technology (MIT) for its annual Mystery Hunt.

The animation begins with the following text: "Wait for it..." on a white background, which stays about 12 seconds, before a montage of scary images, including Regan MacNeil, Pazuzu, and others appear, followed by the message: "Boo! Did I scare you?"

Link
NOTE : the following shock site contain graphic content!
 * mit.edu/activities/puzzle/2010/puzzles/2009/the_zyzzlvarian_holovid_institute/shock.swf