Hey! Deadpool made a joke with a pop culture reference that was fewer than 10 years ago!
Hokage being, of course, a title used by the leader and most powerful member of the Konohagakure, one of the five Great Ninja Villages in the world of Naruto. This famous anime/manga series exploded in popularity for middle schoolers in the U.S. about 2005, to put a date on it, making this one of Deadpool's most current pop culture references to date.
Of course, the comic also "gagged" with the movie Cliffhanger (1993), so maybe that all balances out.