douche ex machina 

Someone who suddenly and without warning, enters an area such as a party, and immediately ruins the mood for everyone else.

The party was really great, until that douche ex machina John showed up and started acting like an asshole like he always does.

douche ex machina by Sarah Bellum June 12, 2008

douche ex machina 

The guy who enters the room while you're watching a movie and then ruins the ending.
Based off of the Greek dues ex machina meaning the "God of the machine" that would enter the play near the end and solve all of the problems the characters would have.

Guy 1: Hey you watching a movie?
Guy 2: Yeah, it's The Sixth sense.
Guy 1: Oh, I love how Bruce Willis is dead at the end of this movie!
Guy 2: Thanks douche ex machina

douche ex machina by bry814 September 30, 2010

douche ex machinist 

A writer of limited talent who weaves a myriad of complex plot lines into the beginning of his work, only to later abandon most of those plot lines in a lazy ‘deus ex machina’ story ending.

Did you watch the ending of ‘Battlestar Galactica’? There was a really douche ex machinist at work on that final episode!

douche ex machinist by AuntyMouse April 11, 2009