The 'Post Ending in X' meme, often referred to as a 'Roll' or 'GET,' originated on anonymous imageboards like 4chan. It relies on the site's sequential post numbering system, where users attempt to predict the final digits of their own post before submitting. The meme usually follows a 'If this post ends in [number], then [outcome]' format, ranging from harmless bets to chaotic demands for the rest of the thread. It popularized terms like 'dubs' (double numbers) and 'trips' (triple numbers), turning the simple act of posting into a game of digital chance. Today, it's used across social media to parody the chaotic luck-based culture of early internet forums.