I did one (that was partially rejected).
It was a screen of a work desk, with phone, monitor, and the like. There was also a picture frame with a run-of-the-mill family photo. My SME asked if I could put a picture of the project owner's dog into the frame... no problem there.
But going a step too far, I created a hyperlink from the dog's picture, and when clicked, went to a hidden screen where a full-sized picture of the dog gave a brief message: "Woof." When the "woof" audio file finished palying, the user was returned to the original screen.
The SME laughed about it, but declined leaving it in the project. (Sigh.)