Lemgthbook

A faction of Facebook groups that substitute the letter "m" for "n" in sharing and commenting. Lemgthbook group names are often parodies of the movie "Fantastic Beasts and Where to Find Them" (ex: "Famtastic ______s amd Where to Fimd Them"), and are usually devoted to sharing cute images.

Not to be confused with Leftbook, but the two aren't always mutually exclusive...