"At drop hat" is an idiomatic expression that refers to someone who is willing to act spontaneously or promptly. It is commonly used to describe someone who is always ready to help or respond without delay. Some synonyms for "at drop hat" include immediately, instantly, promptly, quickly, unhesitatingly, and on the spot. Other synonyms might be swiftly, speedily, without hesitation, without delay, without second thought, and without reservation. These words can be used interchangeably and are typically used in situations where quick action is needed. By using such words, one can convey a sense of urgency and spontaneity in their actions.