Went to a water park with bunch of people and my older sister some time ago. Hot day, and she and I went for the water flume, knowing we’d get soaked. I sat behind her all three times we went, my hands were all over her, pulled her shirt and bikini top up for the cameras on the way down, then joked with her that “I’m going to stick it into your a**” during the last ride. She thought I was kidding, but led me on, saying “Go ahead. Just slide my thong over”, very teasing. Not thinking that was my plan anyway.

Last trip, we hit the top of the hill, before descent, and I tugged her way-short, soaked cotton shorts and, by that point, crunched-up black thong over to one side of her a**, leaned into her, used my thumb to tug my shorts down, and stuck it into her 3 or 4 times during the wet ride down. I was never sure if her screaming and smiling was from the flume water rushing onto us, or, what I was doing to her. But, later in the wave pool, she did get me back by sinking her long-nailed hand down my shorts and grabbing my c***, very hard. Best water park day we ever had.