Wiktionary
n. An off-road motorsport in which competitors attempt to drive a vehicle as far as possible through a pit of mud.
Wikipedia
Mud bogging (also known as mud racing, mud running, mud drags, or mudding) is a form of off-road motorsport popular in Canada and the United States in which the goal is to drive a vehicle through a pit of mud or a track of a set length. Winners are determined by the distance traveled through the pit. However, if several vehicles are able to travel the entire length, the time taken to traverse the pit will determine the winner. Typically, vehicles competing in mud bogs are four-wheel drives. The motor sport is overseen by sanctioning bodies like the American Mud Racing Association, and the National Mud Racing Organization (NMRO), that oversee each class, develop and maintain the relationship with track owners to provide a racer and fan-friendly facility, ensure the sponsors get a good return, and help govern the sport.