My cat knows he's not allowed in the bathroom

[u/Keyguar]

So I sometimes leave the door slightly open and wait for him to try and sneak in. Then when he sees me, he runs away. (He's not allowed in the bathroom because I use plastic bags for the trash can that are at cat height, and he eats plastic. Why? I have no clue. He carves plastic. He can smell it out and will gorge himself on it until he throws up.)