When two people are having sex and one parts the othersass cheeks and gets their mouth next to the butthole and screams.
I was doinking this chick the other night and I rolled her over and gave her a screamer, holy shit she started shaking and had goosebumps all over her ass..
A Terrifying video where it starts out normal and it usually makes the viewer turn up their volume somehow then a loud noise plays accompanied by a creepy face. A great example of a screamer would be a video I saw when I was three: It was just a video of a train and it when down the tracks then it cuts to a black screen making the viewer confused enough to lean in and then a skeleton pops up with a loud noise.