Ferris Bueller had one. Marvel superhero movies sometimes have two. When did it become a thing to have a scene after the credits (sometimes called a stinger)?
New York Magazine’s Vulture column has the history of these extended post-credit scenes, starting with the original “Oceans 11” (the one with the rat pack) and James Bond films’ teasers for the next chapter.
Today, post-credits scenes show up in both superhero and non-superhero movies (like Anchorman 2 and Now You See Me). The only difference now is that each frame is meticulously analyzed and studied after the fact. In fact, the post-credits practice has become so accepted that there are now two apps called MovieStinger and Anything After, which are dedicated to tracking these moments in new movies.