buddy system
noun
(in swimming and scuba diving) the practice of pairing swimmers, each being responsible for the other's safety.
any arrangement whereby two or more persons, teams, etc., watch out for each other, as with mountain climbers.
Origin of buddy system
First recorded in 1940–45
Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019