I Need Your Help Step-sis, Im Too Hard

I am such an idiot sometimes, I took some of my Dad's Viagra to see what it felt like and now I have this raging boner that will not go down no matter how much I masturbate. I am totally freaking out, thank god my parents aren't home or I would be in deep trouble. I burst into my step-sister's room to show her my dilemma and beg for her help. I ask my step-sister Alex to help make me cum to see if my boner will go away, at first she laughs at me and tells me to get out.... but after a few minutes I some how convince my step-sister to fuck me till I 'accidentally' cum in her pussy!