I don't know why but my brain kept reading that as "Black Swan" instead of "Greatest Showman" and I was REALLY confused as to what Wolverine had to do with ballet.
In the X-Men movies, he plays a character (Wolverine) that has claws coming out from his knuckles. If you look closely at the picture, below the oval in the corner, are the two forearms with blades coming from the clenched fist.
PUT ON THE GREATEST SHOW ON EARTH!