"LMAO" stands for "Laughing My Ass Off." It is an internet slang acronym commonly used in text messages and online communication to express amusement or laughter. People often use it in response to something funny, indicating that they found it highly entertaining. This acronym is part of a larger set of internet slang expressions, including LOL (Laughing Out Loud) and ROFL (Rolling On the Floor Laughing). These terms have become popular in digital conversations, especially on social media platforms like Twitter and Facebook, where brevity is essential.