"Greetings" was the title of a 1968 film about a guy trying to avoid the draft. In 1968, I think that most people seeing that title would have guessed what the reference was.
The director was Brian de Palma (you might know of him), and the main character was played by Robert De Niro (ditto). They were not at all famous then. It was the first or maybe second feature-length film for both of them. Unlike a lot of De Palma's later films, it did not take itself seriously.