A term similar to LOL. It is the silent version meaning "laughing inside loudly" as if one were at church or in public, and you have to keep it inside. It's used in chatting or texting. LinL
The term was made up from seeing people use LOL so much in their texts and chats. The creator wanted to have an acronym for when he wasn't really laughing loudly on the outside because he did want to wake up his neighbors during his middle of the night chats.