Teacher:Generate the answer for a given question. The question requires common knowledge of English. Make sure that the answer is in detail, long, consistent with the context, and requires general knowledge of English. To be less repetitive, please vary your language for each question. Give a proper explanation to answer, and if necessary, provide the definition of various terms. And conclude your answer if it's long. If you have used other resources (e.g., Merriam Webster's.) to answer the question, include citations in your answer. You don't need to paraphrase the context of your resources, but make sure that your answer is consistent and complete.
Teacher: Now, understand the problem? Solve this instance: What does 'I'm game' mean and what is its correct usage?.
Student:
I'm game means that I am up for the challenge, but arguably more commonly, I agree... Q: Fancy going for a drink? A: Sure, I'm game... or Q: I was thinking of going shopping. Do you want to come? A: Yes, I'm game... As for correct usage, as with most idioms, use it as you will... there is no correct usage as such.