try sneaking in some public bathrooms where there are not too many people around, then both of you go inside one of the stalls, close the door, and take it from there.. a b-job, hand job, you undressing her and touching her, are enough to turn both of you on.. u dont have to have sex there, cuz it's probably hard, but hey, go with the flow and see what happens.
another thing i have done and works is role playing in bed.. ask her beforehand what turns her on and do that if it also turns you on. For example, you can dress as a policeman, with handcuffs and all, and proceed to arrest her, handcuff her behind her back, strip search her, force her to give u a bj, undress her, fvck her, etc.
or she could dress as something that turns you on.. school girl, nurse, librarian, whatever..
enjoy!