Grant, Cary Easter Egg - Real Name Used in Dialogue in "His Girl Friday"

In a scene in the film "His Girl Friday" (adapted from the play "Front Page"), Cary Grant says something to the effect of "I haven't had so much fun since Archie Leach died."

Archibald Leach is/was Cary Grant's real name. There was no reason for him to include his name in the scene (it had no impact on the story or continuity), so I can only conclude that he did it for the fun of it, and for those movie-goers who were "in the know." A shared in-group joke, as it were. Whether written that way or ad-lib, I think it qualifies as at least a kind of Easter Egg. As far as I know, he didn't do this in any other films.