One of my cat's keeps staring at the corner of the bathroom door. Sometimes he leaps up against the door frame or stands on his hind legs and meows. So I picked him up to show him there was nothing in the corner of the door frame and he climbed onto the top of the door. He just balanced there as happy as could be like a little tight-rope walking cat. I pulled him down so he wouldn't fall and he's back to staring and meowing.
Cat's are weird.