My cat is pretty dumb and I remind him daily.
Whenever he goes to his litter box he always look really mad, like he's wondering why he even has to use it in the first place.
He likes to lay in the middle of walkways and will not move out of the way for anyone. I like to mess with him by sliding him around with my foot until he gets annoyed.
I've watched him jump at our screendoor because there were some birds sitting outside. He face planted it, waited 5 minutes and did it again.
He bullies our dogs and will actively try to steal their treats even though he's the smallest one in the house.
He doesn't know how to play hide and seek. His whole body will be sticking out around a corner but his face will be the only part of him half hiding. Think of Chopper from One Piece when he gets embarrassed.