Go whiz on an eletric fence.
The classic: “If brains were dynamite, you wouldn’t have enough to blow your nose.”
“That boy’s about as sharp as a bowling ball.”
“She’s got a face like three days of bad weather.”
“That guy is ugly as a mud fence.”
“He’s as sharp as a sack of wet mice.”
My little girl likes “animal/body part” insults. From the obvious, like “lizard lips” and “buzzard brain”, to the less obvious “snake elbow” and “gecko toes”. It’s all good. You crab finger.
Might I suggest the following resource
http://herbison.com/canon/fulldeck.html
Other wise “Why don’t you go play in traffic”
Teach your daughter Yiddish. As far as I can see, that language is composed of nothing but insults and curses. 
Your eyes are like pools. Cesspools.
Your lips are like a rose. Thorny.
Your nose is like a basketball. Always dribbling.
If I put your brain on the edge of a razor blade it would look like a BB rollin’ down a four-lane highway.
There’s always the classic “You eat stupid food for breakfast.”
One of my favorites is from The Razor’s Edge, by Somerset Maugham: “I don’t positively hate you all of the time.”
Who said that, and to whom? Was it in the movie remake?
Just a couple of dozen, but somewhat different, at : Funny Cultural Insults
It was not in the movie but in the book, which I’ve read a couple of times. It’s a damned good book, and I can see why Bill Murray was so adamant it be filmed (he reportedly agreed to do Ghostbusters only if they would let him make this movie). It’s said by one of the main female characters to, IIRC, another female character during a drive in the French countryside.
You’re so dumb, you tried to mail a watermelon with food stamps!
“You’re not the smartest bulb in the box.”
“You mean the brightest bulb?”
“No, I mean the smartest.”
The OP should check out the Prarie Home Companion’s (Garrisn Keillor) Pretty Good Jokes CD and books, which are compilations from their annual April Fools Day radio shows. They are primarily G rated jokes, many of which are insult jokes. They should be available on iTunes or Amazon.
One of my faves from a horribly good bad movie (Time Bandits):
“Oh Benson,…Dear Benson you are so mercifully free of the ravages of intelligence.”
or from the Pythons,
“Go away, you electric donkey bottomed trough wiper!”
Or as CDs, right from the PHC website! (Mrs. Map groans whenever I play that stuff, once in a while.)
I picked up a galley copy of a book by Peter Novobatzky and Ammon Shea back when I worked at Harcourt. I kept telling my boss we needed to make it into a multivolume encyclopedia.
You’d probably want to pre-read and censor the content; maybe spoon-feed her little bits rather than let her peruse it on her own.
—G!?!
Some sweat hog mama with a face like a gent
Said my get up and go must-a got up and went
. --Tyler/Perry (Aerosmith)
. Sweet Emotion
. Toys in the Attic
Strong like ox, smart like streetcar!
You’re as smart as a Rock ( and twice as Dense).
You have the ethics and the empathy of a mosquito.
I may not owe you an apology, but owe one to bitches everywhere.
I know you think that you’re right. It’s the tragic reason why everyone around you laughs.
You’re the reason why your Math teacher didn’t want to stop the lecture to define ‘obtuse’.
I don’t think you are stupid. Sadly, I’m sure it’s something far worse…
Yes you are pretty. You had to role high stats Somewhere…
Yes, scrubbing your pores out is a good idea. But asking why the holes whistle is more physics than personal hygene.
No, I won’t say you’re ugly. I’m just not that mean…
Whats that cologne you are wearing? Homeless#5?
I know your feet are tired. I know you want me to rub them. Here’s some soap; come back when they are clean (or at least smell like soap).
Yes that looks good on you. But its less like style & more like Chaos Theory…
When they said legs you thought they said kegs and you ordered two round fat ones.
He’s built upside down: His nose runs and his feet smell.
“Did you eat a lot of paint chips as a child?” <Steven Tyler on AI>
Yo Mama is so fat that when she sits around the house, she really sits AROUND the house.