A website that seems safe enough, but after about 30 seconds has an image pop up that is scary, amusing, or just plain retarded. Also called a screamer (1 and 4) these websites usually have low volume in the beginning or a message for you to turn your speakers up. This is because when the surprise comes it's usually accompanied by a loud noise, like a scream. Usually the page is initially a game or an
optical illusion, something the viewer has to focus on for a while.
These websites are for scaring
the shit out of and
pissing off your friends. The classic one is "Ghost in a picture", where you're supposed to spot a ghost moving in a picture and an "Exorcist" type of face comes up and screams really loudly. There's another, tamer one, where it's supposed to be an optical illusion and then a cartoon man moons you.