What the hell is Tralfamadore?!

Tralfamadore is a fictional alien race that Vonnegut uses in several of his novels. Tralfamadore is the home plant and the Tralfamadorians are the aliens that inhabit the planet.
In Slaughterhouse-Five, Tralfamadore is home to aliens that exist in all times simultaneously. They have knowledge to the future and even know how the world will end, supposed by a Tralfamadorian test pilot. They experience the world around them in four dimensions, having access to past, present, future, and the ability to perceive any point in time at will. The Tralfamadorian way of thinking about time effects Billy's perception of life and death, seeing death as a moment, not an end to existence.  Billy describes the aliens as,

...they were two feet high, and green, and shaped like plumber's friends. Their suction cups were on the ground, and their shafts, which were extremely flexible, usually pointed to the sky. At the top of each shaft was a little hand with a green eye in its palm. The creatures were friendly, and they could see in four dimensions. They pitied Earthlings for being able to see only three. They had many wonderful things to teach Earthlings about time (Vonnegut 26). 


The Tralfamadorains kidnap Billy and Montana Wildhack to put on display in their zoo. 

During Billy's stay in Tralfamadore, he adopts their attitude of fatalism and their response to death, "So it goes.". As he returns to earth he attempts to spread their philosophy.