I went over to my buddy's house to go chill out and watch the game. He was running late when I showed up and he let me know that his sister was home. She goes to the same college as us, and I've seen her around the campus, but now that I was inside her place I got a good glimpse of her smoking hot body! Kate was strutting around her house wearing nothing but a t-shirt and some really revealing panties! Staring at her tight ass was awesome, and rather than tell her I was over, I spied on her to see what this horny teen does when nobody's around! I followed Kate to her bedroom where I saw her rubbing her pussy and masturbating on her bed. I started stroking my cock and she soon spotted me and invited me into her room to pound that dripping wet coochie of hers! I just hope my buddy doesn't mind that I fucked his sister while he wasn't around!