What does she mean by "some clown"?

Native speaker’s answer
Rebecca
By calling the person a "clown", she's calling them a fool or idiot. The use of the word "some" indicates a random person - or clown in this case. She may know the "clown" personally, but she creates distance to the person by using "some" as if she doesn't want to be associated with them. Ex: Some person came by and dropped off flowers. Ex: Oh no! Some clown took my order of food. Ex: You're a clown, you know that?