KJ Apa has been known to show off his chiseled abs on Riverdale, but when he stopped by The Ellen DeGeneres Show on Monday, he showed off way more. While appearing on the show for the first time, the host decided to show the audience the risqué birthday message KJ sent her. In the video, the 22-year-old appears to be shirtless, but when he moves the camera around, you can catch a glimpse of his bare butt in the mirror. While KJ played the whole thing off, he wasn't laughing when Ellen scared him with a man dressed like his character Archie on stage. Watch the hilarious video in full above, then see how fans reacted to meeting KJ ahead.