LMAO means laughing my a** off. It is a common acronym used when something is especially funny. The acronym often appears in texts and online chat rooms.

The "laughing my a** off" phrase is similar to many other hyperbolic sayings where people do something so extreme that a part of their body falls off, whether it be a head, arm, or leg. Some examples of these sayings include "laughing my head off" and "writing my arm off." LMAO is also part of several more elaborate acronyms, including LMFAO and ROFLMAO.