1. The contestants simply see who pisses farther...or pisses more. AKA a pissing contest.
2. The two contenders attach their urinary tracts via some form of tube with the use of a waterproofing substance and a glue of some sort. The two people proceed to drink a defined amount of a liquid (say one gallon per person or something of the sort)...then the waiting begins.
The two people then begin to piss. As the urge to urinate increases an epic piss battle begins to ensue. The golden liquid will then be pushed between the two people until eventually one of the combatant's bladders bursts. (More liquid may be ingested by combatants if a stalemate ensues or if not enough liquid is present for a bladder bursting...or surrender.)
History: Piss battles have been an effective way of testing the manhood of males for centuries. Since the prowess in battle is directly linked to the genitals of the combatant, the winner is said to be more sexually potent then the loser.
Piss battles are known to cause cancer in the state of California.