Hello, last week I went with a friend to a gay party. There were many people around having sex, though I went just to look. Suddenly a man who was masturbating nearby came from my behind and grabbed my butt hardly. He even touched my intergluteal cleft, though I do not think he did touch my anus but he was very close. He probably had semen in his hands (his own or someone else's). I quickly twisted my body and told him I was just there to look and did not do anything. I am sorry for being so descriptive. I have been very worried as I do not know this man and his behaviour. Am I at risk? If so, what are the chances? Looking forward for your reply, thanks!