Francisco d'Anconia
Master Don Juan
Besides, if she's too young to go to the same clubs or bars that you do what's the point (other than you copping 12-paks for her and her friends to sneak back into the dorm). 
You've said it a hundred times. Maybe a thousand. And every time you say it, you train your brain to freeze the next time she walks into the room.
Leagues are a myth invented by guys who are scared of women.
She's a person. She has bad breath in the morning. She picks songs she can't sing in the shower. She overthinks her own texts.
Walk over. Say something. The league dissolves the second you open your mouth.