Brown Chewing Gum is a video published to YouTube on September 12th, 2010 by the user IHadThisNameFirst. The description tells you to "turn up your sound", a common bait and switch.
It initially shows a video of Brown, a character from the British Nickelodeon animated short film Purple and Brown chewing bubble gum, with appropriate chewing noises playing. Approximately 17 seconds later, the screen changes to a man without eyes that comes from the Daneboe video Scariest Faces, with a loud scream playing.
NOTE: The following video contains a screamer.