From BR Bullpen
The mercy rule is a provision in the rules that terminates a game early if one of the two teams has taken a substantial lead, considered to be insurmountable, after a minimum number of innings have been played. The rule is designed to avoid humiliating losses and to prevent unduly extending games whose outcome is no longer in doubt. The mercy rule is often called the skunk rule in slang, particularly in youth baseball.
Mercy rules are common in baseball outside Organized Baseball, having been used in college baseball, the Korea Baseball Organization, Little League, the Cuban Serie Nacional, international events such as the Baseball World Cup, the World Baseball Classic and some European leagues. In games governed by a mercy rule, the contest is declared over if one team is ahead by a set number of runs (usually 10) after a set number of innings (often 5 or 7).