1. A contest, usually between two males, to see who can urinate over the longest distance, or for the longest amount of time.
2. A contest in which logical rational argument in the search for truth gives way to emotional and/or personal attacks for the sake of power or reputation. Usually such contests leave a feeling of ill-will amongst all involved, and prove nothing more than who belongs where in a primal heirarchy.
Derived from the term "pissing grounds", which are usually urinated on to mark ownership.
What started out as a rational debate quickly degenerated into a pissing contest.