Yall girls are weird.?

Me and this girl talkin on the bus and she knows i want to go out with her ive done asked her out before shee says ill think about it ( it means no i know already.) she got up to get off the bus and i smacked her on the *** and she turned around and smiled at me ( confusing part ). her little bro is 9 ( maybe ) im 15 he asked me to go to their house to play with him cuz he dont have many friends that can. I told him i would but his sister wont tell me yes. ( now he on my side and is badgering her to say yes ) she said maybe and kinda did a cute little grin at me. what the hell is she thinking? im just wondering its not like im desperate i got her friend trying to go out with me but i dont like her.