"FAF" is a slang term that stands for "Funny As F***", which is often used as an expression of amusement or to describe something that is hilarious. There are several synonyms for "FAF" that can be used in its place depending on the context and the level of humor that needs to be conveyed. Some of these synonyms include "hilarious", "side-splitting", "gut-busting", "humorous", "amusing", and "comical". Choosing the right synonym for "FAF" can help elevate the humor in an exchange and make the conversation more engaging and enjoyable for everyone involved.