CTFU means âcracking the fuck upâ, and is quite similar to the acronym CDFU, which means âcracking da fuck upâ. The acronym CTFU is also similar to âLOLâ (laugh out loud), âLMAOâ (laughing my ass off), âLMFAOâ(laughing my fucking ass off), and other slang acronyms in that they all show that the user is laughing.