get it into your thick head idiom
mainly UK (US usually get it through your thick head)让你的榆木脑袋开窍
to make someone understand something, especially when you have told them many times before and are annoyed
How can I get it into your thick head that it’s dangerous to swim that far out in the sea? 我怎么才能让你的榆木脑袋开窍，明白游出海太远是危险的？