What is LMAO? THIS is What LMAO Means! OMG, ROFL, BRB, AFAIK, BFF, SMH ... Jun 4, 2019 LMAO is one of many common words used in text messaging, instant messaging, chatting, and on Facebook and Twitter. At one time or another, you've probably seen this Internet slang. ... LMAO is an acronym that stands for Laughing My Ass Off. Many people say (or text) this acronym when they find something particularly funny.