The Captain Underpants meme originates from the beloved children's book series by Dav Pilkey, featuring the alter ego of the grumpy Principal Krupp. The character gained a massive second life in internet culture following the 2017 animated film, where his signature 'Tra-la-laaa!' catchphrase and boisterous, misguided confidence became perfect fodder for reaction images. Usually, the meme captures themes of unwarranted enthusiasm, silly bravery, or childhood nostalgia. It’s a go-to template for situations where someone is acting heroically in the most ridiculous way possible, resonating with both original fans of the books and a new generation of meme creators who enjoy the absurd visual of a man in his underwear fighting crime.