"Does top your head" is often used to describe someone attempting to recall something from memory quickly without much thought or preparation. There are several synonyms that can be used interchangeably with this phrase, including off the cuff, on the spot, impromptu, spur-of-the-moment, ad-hoc, and extemporaneous. These words all describe something being done without prior planning or forethought, emphasizing the spontaneity and improvisation required. Whether it's a brainstorming session, a pop quiz, or a conversation with friends, these words can all be used to describe a situation where someone is asked to respond without much preparation or warning.