The Diet Coke and Mentos meme stems from the famous physical reaction between carbonated beverages and Mentos candies, which creates a spectacular soda geyser. While the experiment became a viral sensation in the mid-2000s thanks to early internet culture and YouTube, it eventually evolved into a popular metaphorical meme template. It is now widely used to represent a small catalyst causing a massive, uncontrollable reaction—whether it's a single comment sparking a heated online argument or a minor inconvenience leading to an absolute emotional meltdown.