"also well known by the slightly less polite term slaughter rule (or, less commonly, knockout rule and skunk rule),"
Widipedia
"A mercy rule, also well known by the slightly less polite term slaughter rule (or, less commonly, knockout rule and skunk rule), brings a sports event to an early end when one team has a very large and presumably insurmountable lead over the other team. The mercy rule is most common in games such as baseball or softball, where there is no game clock and play could theoretically continue forever, although it is also used in sports such as hockey, football, and American football. It is very rare in competitive sports beyond the high school level."