Agor.io
From Screamer Wiki
Agor.io
As soon one opens this website, a picture of Jeff the Killer that inverts negativity at a seizure-inducing rate pops up with a ear-piercing scream. When one tries to close the website, a window pops up with the text "U SCARED BRO LOL", leading the user to having to force-quit their web browser.
Media
There are multiple social media posts such as this one on Reddit about the site. This one in particular was supposedly written by a parent whose nine-year-old son had an epileptic seizure when trying to play Agar.io because they misspelled it as Agor. The mother states she is talking to a lawyer and is attempting to track down and prosecute the creator of the Agor.io website.