I'm inphraseI agree to join or take part; informal.“You're ordering lunch together? I'm in.”I'm down for thatphraseI like that suggestion and am willing to do it; informal.“A movie after dinner? I'm down for that.”Count me inphraseInclude me; I want to participate.“A weekend hike? Count me in!”Yeah, I'm comingphraseYes, I'll be there or join you.“Are you joining us for lunch?” “Yeah, I'm coming.”