It's easy to get a guy turned on, all ya gotta do is talk to him about what happened last night make something up like last night my mom and dad were "doing stuff..." like I could hear them both moaning histerically ! and it was weird , another way would be showing off ur body , wear tank tops, tight skinny jeans, or perhaps mini skirts and if u have thongs pull them up high (not too high) just enough for him to see it while wearing these cloths. If u want to get him REALLY HORNY all ya gotta do is get next to him some how like whispering stuff to him while slowly rubbing his knee, trust me this doesnt make him freak out or anything or feel awkward but he'll get a boner and be too stupid to think about anything.
You do a lap dance on him and rub your boobs in his face. That is a good place to start. You could also go down on him and do oral.