On Snapchat and other social media platforms, “FDU” typically stands for “F***ed Up Decision.” It’s often used to describe a situation where someone has made a poor or regrettable choice. The abbreviation can be seen in various contexts, usually as a way to express frustration or disapproval regarding someone’s actions. As with many abbreviations and slang terms, the meaning can vary based on context, so it’s always good to consider the surrounding conversation for clarity.