1st Definition: An examination process by reality show semi-fanatics to aid in the pre-determination of events in any given television show's un-aired episodes. This method of gathering clues may consist of scanning posted screenshots, and the indexing of local eyewitness narratives, weather reports, or local media news for making a "best guess" effort at the predicted outcome. It's a science or a black art. You decide.
2nd Definition: Activities as described in 1st Definition above usually performed by someone who has absolutely no social life and/or no grip on reality. The spoiler uses his/her "spoiling" of a reality show to attempt to find reality in his/her own life. Pathetic or pathological. You decide.