After my friend went to college I was approached by his parents and asked if I could help to get his younger sisters grades up by tutoring her a few nights a week. My friend had asked me to watch over his sister because he thought she was kinda nieve and the boys were starting to notice her now that she had turned 18. She was so nerdy with her braces that I couldn't help but get a hard on when she entered the room in yoga pants and a bikini top. As we were studying I noticed her continuing to glance at my bulge with this look of amusement and that she was rubbing herself thru a little hole in her leggings as I was reading the text book dialogue. Once I had her attention on my my dick about to bust through my pants I decided to unzip em but before I could she had already had em undone, and her cute lil brace face and wet mouth purring against my swollen head. All while one hand between her thighs and two of her fingers buried in the hole in her pants, I said, "I think we are going to have to step the study sessions up to 3 times a week so we can get your ass used to the routine. Of course she agreed saying, " please do what you want to me for as long as you want. That's when she whipped her phone out and started recording before leaving the job as cameraman to me .