The Trojan Horse meme is based on the legendary Greek myth where soldiers hid inside a massive wooden horse to infiltrate the city of Troy. In internet culture, the template typically features a labeled wooden horse being pulled into a city, representing something that looks like a gift or benefit but contains a hidden catch or 'gotcha' inside. It became popular for describing software updates, social interactions, and political scenarios where one thing is disguised as another. The visual metaphor remains a staple for pointing out ulterior motives in a humorous, relatable way.