What people have to understand is that if a girl wears a 'hijab' that doesn't necessarily mean she's religious, heck more often than not 'hijabis' are less religious than muslims girls who don't wear the hijab. This is because in most muslim familes, hijab is forced upon girls from a young age (this is not allowed in islam and is merely a result of cultural beliefs) and as a result a lot of girls stop wearing it when they're older or they don't understand what it means to wear it.
If you try to understand hijab, it doesn't simply refer to the headscarf or sometimes full 'niqaab' that girls wear but it refers to being modest around guys, in their behaviour as well. The same applies to guys, 'lower your gaze' is what we are told in Islam, when it comes to girls and guys.
What I would request from all of the guys who want to 'hit' a hijabi is please ask her to take the hijab off before you indulge in any intimate activites as it is a huge disrespect to the hijab.