"How would your best friend describe you?"
This answer can be short. Use key words that show how you are a good fit for this position. If it if a salesperson, mention things like, an easy person to talk, good personality, and dependable as the traits. But if it is for a manager position, then you can use different words like organized, helpful, considerate, and smart. So it all depends on the position. Most people will be honest and say what the best friend will actually say, but it is more effective to choose the words so it relates to the job. Here are some examples."Oh, let's see... I think my best friend would describe me as honest, detailed, and very organized.""I think my best friend would say that I'm very responsible. Whenever our group of friends had to coordinate an activity, they always relied on me.""My best friend would probably say that I'm warm, friendly, and understanding."
It doesn't have to be long, but don't blurt out the answer without thinking. Then it makes it appear as you are thinking about it instead of saying an answer you already prepared.