The 'Thanus' theory is a viral internet phenomenon that emerged in early 2019 ahead of the premiere of Avengers: Endgame. The core premise suggests that Scott Lang (Ant-Man) could have bypassed Thanos's immense durability by shrinking down, entering the Titan's rectum, and rapidly expanding to lethal proportions. What began as a fringe Reddit theory quickly exploded across Twitter and YouTube, resulting in thousands of memes, fan animations, and even mock interviews where the MCU cast was asked to weigh in. Despite the directors eventually debunking the physics of the move, it persists as a legendary piece of Marvel fandom lore, used to mock the complexity of superhero plotlines with absurdly simple solutions.