OK, it is more of just a pun, and the “of the day” part is a stretch. This is probably more of a once-in-a-lifetime thing. There was an episode of the TV show House where the patient had too many spleens. I was surprised they didn’t work this joke into the dialogue!
Daughter: Taylor’s uncle found out that he had more than one spleen.
Me: Well, then he has some ex-spleening to do.
You can start groaning . . . . . . . . . . now!