They are asking for it.
Just not from you. If Brad and Chad would go up to her and grab her ass she'd be smiling and already imagining how she'll get dped later on.
If you try it, you get a visit from the police for attempted rape.
Them saying that they're not asking for it is just their natural anti-slut defense, in order to uphold their "pure" social status even if the whole football team fucked her already.