A small serpent
A tiny snake that you can’t even trust to do something right. They’re as dumb as a bag of rocks and fail at everything like it’s their full-time job.
My cousin is a small serpent. He promised to clean my room and now it looks like a tornado lived there.
That kid in class is a small serpent. He tried to solve the math problem and got it wrong twice.
My neighbor’s dog is a small serpent. It chased my cat and then ran into a tree.