"You're disappointing and you have no brain."

I'm going to set the scene for you.

My favorite little red-head is 8 years old. She's smart, spunky, and has an attitude that she blames on her red hair.

My Dad, her Papa, said something to her that made her mad. I have no idea what he said because I wasn't paying attention. Whatever was said was probably was not that bad.

My favorite little red-head went right up to her Papa, looked him in the eye, told him something and then walked away.

She said: "Papa, you're disappointing and you have no brain."

And then I died in a fit of laughter. 

That insult is direct and concise. It's clean, with no cussing and she didn't even raise her voice when she said it. Her tone was even, her delivery was perfect and she was confident in her wording.

I give it a 10 out of 10. It's the perfect insult. 

"You're disappointing and you have no brain."

Also, I feel that way about a lot of people in my adult life. Thank you, little redhead, for giving me the perfect words and the perfect insult. I'm going to put that one in my back pocket and save it for future use.