The absolute kinkiest thing I ever did was a group masturbation thing with guys and girls. I was still in high school when it happened. We did it before and all had a great time. I got to see all of the girls I wanted to naked. There was a lot of partying going on before it happened. It started with these two girls putting on a show for us all with dancing and eventually kissing. Everyone was getting horny. Someone yelled for them to strip and they started taking off each other's clothes. As time went on they were standing and kissing each other in just their underwear. It was so hot!
All the guys pants were bulging out including mine. Dudes started kissing on their girlfriends and eventually someone pulled his dick out and started jerking. I joined right in and soon others did too. I loved being basically surrounded by young cunts all getting fingered.
Of course this is kinky. But that's not the end of the story. As I looked to my left I could see my step sister fingering herself. She was staring right at me with three fingers in her hairy pussy. I stopped for a moment and just looked. She spread herself open for me. It was no accident. I went back to jerking and very quickly came all over my legs and hands. She actually started to smile at me and my orgasm. Needless to say we have watched each other a few times after that at home.