[m4f] a different kind of vacay, with horny sis

She starts off in the car, we have a 3hr drive to the beach. Being very sneaky she starts to get a lil handsy with me. I try to fight her off at first but I'm too weak and give in. My heart's beating fast with out parents sitting right up in front of us. "Sis stop" you see me mouth the silent words to you, and you just smile.