TFK means: initialism of The Fartknockers, a trolling organization that is primarily active on social media, such as YouTube and Discord, and targets certain users with harassment, doxxing, smear campaigns, and. It is internet-era slang, commonly seen on TikTok, Discord, Reddit or X. There is no real cause for parental concern; it is descriptive vocabulary rather than risky behaviour. If your teen uses it, context will usually make the intent clear. A short, curious question about where they heard it is usually all that is needed to know whether to follow up.