Jimmy Kimmel helped one of his writers pull a prank on his roommate. The writer, Jack Allison, decided it would be fun to prank his roommate Mitch, who fully believes in ghosts. Unfortunately for Mitch, Kimmel is a master of pulling pranks. Sometimes he even gets in people's heads by assuring them they're not being pranked. But in this case, Kimmel had a full production crew and cameras rolling in order to scare poor Mitch to death. Mitch's fear of ghosts ensured he never had a chance, and it also confirms that Jack is the meanest roommate on the history of the planet. Not as mean as this boyfriend who pulled a ghost prank on his girlfriend, but pretty close.

The Kimmel crew went all out, building suspense and fright just like in a horror movie. Odd things began to happen to Mitch, which at first seemed like they could be anything other than the supernatural. Living in the age of smart phones, Mitch also used his phone to text people about these stranger occurrences. Those bumps in the night could mean animals, or in the case of Los Angeles, an earthquake:

Shaking Mitch to his core.
Jimmy Kimmel Live
Sources: Jimmy Kimmel Live