Because of a friend's tip I found out that when my sister is drunk she gets completely wild and she fucks the first guy she sees. I gave it a shot, we planned to go to a night club with some friends and asked everyone to meet us at my flat. Only me and a friend was there when she came. I invited to have some drinks before we go so we will fell more joyful when we got to the night club. After some vodka shots her real self started to show, I fucked her and got more than I was expecting.