The term "sock monster" refers to the common phenomenon of losing socks in the laundry. Many people experience the frustration of washing a pair of socks only to find that one sock is missing after the cycle. This has led to the playful idea that a mythical creature, often called a sock monster, is responsible for the disappearance of lone socks. The sock monster is not a real creature but rather a humorous way to explain the mystery of missing socks. Various theories suggest that socks can get stuck in the washing machine, dryer, or even behind furniture, contributing to the ongoing mystery of where they go.