Meet Doom and Gloom. They're sort of friends. Doom is mischievous and always pretends to be helpful. Gloom is always depressed but hopeful in spite of Doom being Doom.
In "Happy" New Year, Gloom is depressed over how bad 2016 has been. 2017 would probably be worse. In Gloom's mind, everything has a snowball effect. Doom being Doom, seizes the opportunity to mess with Gloom by telling him that the world is going to end. Gloom being Gloom, is content with humanity's fate until he finds out the truth about Doom's cruel joke.