cobwebbed cranium

Someone who hasn't used their brain in a long time, stupid.

A: I'm smarter than you
B: Nah, you have a cobwebbed cranium

cobweb head

somebody whose head is obviously devoid of anything else.

I have to go meet Mike because he ran out of gas again. He's such a cobweb head.

cobweb rocket

To have a cobweb rocket

Having a dusty "rocket" or penis

When you haven't had sex in a while your rocket gets cobwebs on it

Your dads cobweb rocket