The Uncle Sam meme is based on a 1917 recruitment poster created by James Montgomery Flagg for World War I. Featuring a stern-faced personification of the United States pointing directly at the viewer with the caption 'I Want YOU for U.S. Army,' it became one of the most famous images in American history. In the digital age, the 'I Want You' format has evolved into a versatile meme used to recruit people for specific causes, call out specific individuals, or create authoritative jokes. It remains a staple of internet culture for its immediate recognizability and commanding visual style.