John Cena -- Black Eye For The WWE Guy ... Sporting Epic Shiner

Score another black eye for the WWE ... John Cena proved again how real the sport is with his fresh new panda eye.

Cena was snapped in Glasgow Wednesday showing off an Irish makeover ... but we're not exactly sure how he got it. It's a safe bet to assume he picked it up while grappling with a dude in a cod-piece.

It's apparently a great week for shiners ... supermodel Christie Brinkley got banged up Monday when she did a Fabio and took a bird to the face while vacationing down in Turks and Caicos.

Together they make a matching set.