This is an expression used in place of 'lol' and various other MSN abbreviations, such as 'rofl' and 'lmao'. It stands for Laugh Out Loud My Arse Off. Use it when you want to take a stand against people using MSN speak.
Person: Oh, that'sso funny. Lol.
You: Lolmao, you mean.
A portmanteau word that is made up of 'lol' and 'lmao' that stands for "Laugh Out Loud My Ass Off". It is often used to express one's feelings when they find something extremely humorous. This abbreviation was accidentally created by an Instagram group chat called 'gang bang'.