The 'That's My Secret' meme stems from a pivotal moment in the 2012 film 'The Avengers.' Just before the Battle of New York reaches its peak, Bruce Banner reveals to Captain America that his secret to controlling the Hulk is that he is 'always angry.' This dramatic transformation became an instant fan favorite. On the internet, the meme is used to explain why someone is surprisingly good at a difficult task or to reveal a relatable, constant state of being, such as being 'always tired' or 'always hungry.' It remains one of the most versatile templates for expressing hidden resilience or humorous personal habits.