You can't get the simplest little thing through your thick skull.

My wife says I've just got a naturally thick skull.

Why is that people can't get this through their thick skulls?

Which is why I mean to beat the need for care into your thick skull.

Get that into your thick skull before you go crazy.

Therefore, he can be killed if anyone is strong enough to break in that thick skull of his.

It was stuck like a broken record in his thick skull.

Get that into your thick skulls and make it happen.

It took my thick skull several minutes to evaluate the situation.