Why does this guy only talk to me when he's with another girl?

okk...so there's this guy who's a player. He was talking to me like twice & he was flirting with me. I know that hes a player, and I know that only stupid girls like players. BUT...I can't help thinking about himm...and i think i may like him. The thing is...he only says hi to me when he's with another girl. He'll say stuff liek "heyyyy....i know you!" and smile.What does this mean?? I am confused?? I don't want him to know that i fell into his game. What do I do so that he thinks that I don't care about him even though i do? THANKS