Several people are credited as "Special Thanks (with tongue)".
The opening credits are descriptions of the actors rather than the name.
SPOILER: Opening credits written from Deadpool's perspective.
The scene after the credits shows Deadpool in a bathrobe, making fun of you, the viewer, for sticking around for so long. He also talks about the sequel, and says it will feature Cable. Then he makes a few jokes about the casting, and pokes at other movies that usually tease future movies in these scenes.
The scene after the credits, with Deadpool in his bathrobe, is an homage to the post-credit scene in Ferris Bueller's Day Off. The final "chika-chikaa" he does refers to the song "Oh, Yeah", by Yello, which is featured in that movie.
The main credits, including the title, aren't revealed until the end of the movie.
A cartoon version of Deadpool runs wild around the credits.