A piece of work
The kind of person who will ruin your day just for fun. They're like a giant pain in your butt who never stops talking nonsense.
My friend is a piece of work. He made me late for school just so he could argue about which cereal is better.
My dad is a piece of work. He turned my homework into a 10-minute rant about why the moon is made of cheese.
My sister is a piece of work. She made me miss my bus because she was too busy arguing with a robot.