the Western zoo said:it's like a gag where someone sends you a link to an image and there mostly a text saying something like "take a very good look at this and remember as much of this picture as possible" and then you of cause focus intensly because you think they're going to change something in the picture and make you point it out... after a while the picture changes to something scarry and a very loud noise goes off - BANG, you've just pied your pants...
I think he was asking which screamer in particular... instead of "what is a screamer"