What Is The Derpiest Thing Your Cat Has Ever Done?

We have cats and fish aquariums. One aquarium was pretty big and the lid strong enough to hold our kitty who would jump from adjacent furniture onto it, then lean his head over to watch fish through the glass. One day my husband was cleaning aquarium and took lid off. Cat who was normally very adverse to anything out of the ordinary—such that his name is Skitty, that is skittish—did not notice. He did his normal jump and landed all four feet in the water! His expression of surprise was cartoon-worthy! Huge eyes! I quickly went to help him out but he managed to grab the adjacent bookshelf and rapidly claw his way up and out. Fish were ok too. That was at least 8 years ago and still cracks me up.

Years ago my husband and I came home late, flipped on the ceiling light and startled the sleeping cat, who spazzed out and fell off the bookcase. She started staggering around in circles and, envisioning every possible brain/spinal/neurological injury, we raced in a panic to the 24hr emergency vet. After several hours and several hundred dollars we were informed that she had, in the most clinical of terms, knocked herself silly. (By this point she was acting fine.) She lived to be 18, outliving both of her littermates by 2 years.

My cat gallops like a horse when he gets scared

At a previous house we moved to, we brought three cats with us. In the first month, all three cats jumped down in the space behind the washer and dryer and got themselves stuck. Each at a different time. All three times, I had to kneel on top the washer, lean my upper body behind the the machine, and reach to pull the cat out. Thankfully, despite my average height, I have long arms.
They never did that again!