Crystal Brain

A person that's so much of an idiot that you could actually see through their brain, and of course there is no brain cells.

John: I just broke your cat's leg for fun!
Miranda: You fucking crystal brain, you're so fucking stupid that everyone, even the stupid know you're stupid

tinker-twat

A fool and a twat.

Trent: Brimmy, shut the fuck up!
Brimmy: Trent, you shut the fuck up you bloody tinker-twat