Hot Tub Hanky Panky

You and your girlfriend invited up your best friend for the weekend at your mountain cabin. He's brought his new girlfriend, and you all have a great night. Your best friend and girlfriend both pass out early, however, and you find yourself alone... in the hot tub... with your best friend's girl. After a few moments of blatant flirting from her, she begins her true seduction. She takes her top off, and gets you hard for her. She tells you it would be easy to ride you in the hot tub without anyone noticing... In fact, she's pretty sure you can cum inside her before anyone comes outside.