Jim Parsons, who plays Sheldon Cooper on the show, posted a picture to Instagram of what looks like a pretty tasty cake which was decorated with a "happy birthday Kaley" message.
Now, that all seems lovely but there's just one small problem here – Jim, in a move that only his character Sheldon could pull off, actually posted the picture before it was given to Kaley, completely ruining the surprise!
It was by accident though, right? Nope, it seems like Jim / Sheldon was pulling a prank, tagging Kaley in the caption.
And moments after posting the picture, he showed that the surprise was well and truly ruined by uploading another one of Kaley looking miffed next to his original post.