Her room(Femdom)

You appear lying on your sisters bed with her standing in the doorway. You realise your naked from the waist down revealing your ass to her. You realise she is also naked from the waist down, only having a bra on. You also realise something that makes realise what this dream will be about. You see that your sister is wearing a strap on. She them climbs on top of you and thrusts the strap on into your ass.