The idiom 狼狈为奸 is formed by combining 狼 (wolf) and 狈 (a mythical creature described in folklore as having short front legs, requiring it to lean on a wolf to move), which together represent two entities cooperating, followed by 为 (to act as) and 奸 (evil or treachery), resulting in a literal meaning of "wolf and bei act as evil" to metaphorically depict collusion in malicious activities.