The first time happen after a friend's birthday party. When we left the party, my sister and I were a bit drunk and I bet with her that she wasn't able to go strait until the car, she only had to walk and keep her feet on the parking lines on the floor at the parking lot. Well, she fell on the floor half way and when we get to the car she gave me her first blowjob. This was the third time, but the first sober.