Agor.io
From Screamer Wiki
When you open this, an screamer of Jeff The Killer Pops up with an ear-piercing scream so i recommend you don't search it up but if you do here is info
But wait, if you want to close it, its better you reset your PC/Mac or anything (less phones), because this pop-up with a message "U SCARED BRO LOL" so, be careful, this also would make you get a seizure! don't misspell agar.io! And....Warning! I KILL U >3
Nope XD