Wow, now I even know how poker game works! ^^ Thank you Pascal and Lee :)

I think Lee's answer makes sense, it came from a poker game.^_____^ Here are some rules of it. 1.CHECK - If there is no wager on the current betting round, a player may check. The act of checking passes the action to the next person, immediately clockwise from the player. A check does not forfeit interest in the pot, only the current right to bet. If all active players check during a round of betting, the round is considered complete. 2.BET - If there is not yet a wager on the current betting round, a player may bet. If a player bets, the player immediately clockwise from him or her (and any subsequent players) may fold, raise, or call. 3.FOLD - The act of folding forfeits all interest in the pot. A player who folds is not required or allowed to wager any further money during the current poker hand, but cannot win that hand either. 4.CALL - If there has been a bet on the current round of poker play, a player may call. The act of calling requires the player to match the current bet made by his or her opponent(s). 5.RAISE - If there has been a bet on the current betting round, a player may raise. The act of raising requires the poker player to match the current bet, and then make a greater one. All subsequent players are required to call the raise or raise again ("re-raise") to maintain interest in the pot.

It's 'call,' and it means 'yes, go ahead, let's do it....'. I hear it's from poker, I don't really know what it means in it though.

No, it means "ok, why not(let's do it)" ^^ I guess it's kinda slang.