Could you give some examples for the expressions like "someone's in", "I'm in"?
Answer from a Native speaker
Similar expressions are "count me in," "I'm down," "include me," and "sign me up." Ex. A. What do you say, want to do a road trip across the country? B. Count me in! Ex. A. Do you want to go to yoga with me on the weekend? B. I'm down!
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