Types of people

Does it matter if someone says you're no rocket scientist? Yes,it does! This phrase means not very intelligent.

What if a newspaper describes a politician as a dark horse? This means nobody knows much about him.

And a party pooper? This means a person who spoils enjoyable activities by refusing to join in. This idiom is also useful in apologies: '' I'm sorry to be a party pooper, but I have to go home now".