When we talk about synonyms for the word "did off top your head," we refer to the ability to recall information from memory without any preparation. Some common synonyms for this type of thinking include spontaneous, impromptu, unscripted, and extemporaneous. Other common terms include on the fly, off the cuff, and ad lib. All of these terms describe the ability to think quickly and come up with ideas, responses, or solutions in the moment, without relying on any prior preparation or planning. Whether we're brainstorming ideas, participating in a conversation, or presenting in front of an audience, the ability to think off the top of our heads is a crucial skill that can help us succeed in many different situations.