Players.

Yesterday, one of my male friends referred to me as a player. Now this is not my first time being called a player, but I'm really confused as to why people think I'm one. I'm friends with a lot of guys, mostly because it  is so much simpler to be friends with a guy than with a girl. I hang out at our school's gym where, of course, there are much more guys than girls. And I smile a lot. I don't flirt with people that I don't like. Where is this reputation coming from? Answer me people! What do you define a player as?