Kathrine

It's pouring rain. Your 18 year old stepsister and you decide to hit the back yard to play around in the rain to cool off after the heatwave that just ended. It is a refreshing time and you both enjoy it immensely. During your fun, Kathrine throws a handful of mud at you, which you of course do the same to her, both of you howling in laughter. By the time you are done, you are both soaked and covered in mud. She looks at you and says "Bath time!", strips down to nothing and run inside towards the bathroom.