somebody can't get it into their (thick) skullspokenUNDERSTAND someone is unable to understand something very simple 某人的笨脑袋无法明白 He can’t seem to get it into his skull that I’m just not interested in him. 他这个笨蛋好像无法明白我根本对他不感兴趣。
→ somebody can’t get it into their (thick) skull at skull(1)