My office is full of wannabe jokers, but this one did make me laugh.
The guy with his back to my camera with his arms behind his head is asleep at his desk. He always does this in exactly the same pose, pretty much every day.
The guy holding the banner up caught him on camera a while ago and made this banner, and holds it up everytime he catches the other guy sleeping.
I managed to get a snap of it this afternoon.