If its obvious shes trying to pick you up (she asks in a starbucks/commons while youre studying, and you dont know her) then give her the paper and LET HER PICK YOU UP... make a conversation out of it.
"What for - nothing dirty, I hope?!"
If its in class and shes just turning to you cuz she knows you then correct her attitude. Respond to her quiry:
"uhhh... <girly voice>Anthony can I pleeease have a sheet of paper?"
She will sas you, and say it with a really cutsie tone.
"No, you may not. But thanks for asking so politely!"