A sudden and disastrous halt in the music 'set' played by a DJ. Often associated with the music styles of House and Techno where a set can last for an hour or longer. This calamity results in the loss of rhythm and ‘flow’ in a club or rave, which in turn presents a certain negative attitude by the attendees toward the DJ. This is best defined as ‘boo’. This condition often throws the DJ into an extreme state of apprehension and a fevered determination to save his cred usually resulting in an increased chance of causing another train wreck. Technical problems associated with equipment do not qualify under this definition. Derived from the visual image of a train, traveling at high speed, smashing into an brick wall.