"Doth top of your head" is a phrase often used to describe something that is known without much thought or consideration. The spelling of "doth" is pronounced as /dʌθ/, which is the Middle English equivalent of "does" in modern English. The spelling of "top" is pronounced as /tɒp/, which refers to the highest point of something. Together, the phrase means that something is known to someone without having to put much thought into it, similar to something that is sitting right on top of their head.