What did someone do that made you think they were really smart?

 People can demonstrate their intelligence in various ways, and there isn't a single action that universally defines someone as "really smart." However, there are certain behaviors or actions that can indicate high intelligence. For instance:

1. Problem-solving: When someone quickly grasps complex problems and comes up with innovative and effective solutions, it often indicates high intelligence.

2. Quick comprehension: The ability to understand intricate concepts or ideas swiftly, especially in unfamiliar or challenging fields, showcases intelligence.

3. Adaptability: Smart individuals can adapt to new situations or environments seamlessly. They can learn from their surroundings and apply their knowledge effectively.

4. Critical thinking: The capacity to analyze situations objectively, evaluate information, and form reasoned judgments showcases intelligence.

5. Creativity: Intelligent individuals often demonstrate creativity by generating novel ideas, approaching problems from unique perspectives, or creating innovative solutions.

6. Strong memory: While not the sole indicator, a sharp memory that retains and recalls vast amounts of information or experiences can signify intelligence.

7. Effective communication: The ability to convey complex ideas in a clear and concise manner is often indicative of high intelligence.

Remember, intelligence is multifaceted and diverse, and someone's demonstration of intelligence in one area may not necessarily apply universally across all domains. People can exhibit their intelligence in numerous ways, and it's essential to appreciate and recognize various forms of intelligence and talents.