Insults:

You call people to ask them for their phone number.
You must be the arithmetic man -- you add trouble, subtract pleasure, divide attention, and multiply ignorance.
You must be from the shallow end of the gene pool.
You may be a beauiful person on the inside, too bad you were born on the outside!
You're a few fries short of a Happy Meal.
You're a few planets short of a Federation
You have Diarrhea of the mouth; constipation of the ideas.
You're so dense, light bends around you.
Your family wasn't dysfunctional until you arrived.