I witnessed two co-worker’s sexual behavior at work. Should I report it? One co-worker has expressed hostile behavior towards me at work. But because no one saw or heard anything, I was unable to prove it. Nor did anyone but me see the two engaging in sex, so I cannot prove it, just like the hostility expressed at me. What should I do? Follow-up: We have cubicles and I happened to go towards the copier to make copies and she was showing him her private part. When she saw me she quickly put her dress down and he walked away. Just two weeks ago this guy had been desrespecting me and I brought it to my boses attention. Only when it happened twice did he call in an outside hr department to investigate and because he denied it it wasn’t considered a hostile environment just an employee issue they would deal with. Now, everyone has to fill out job descriptions and get sensitivity training and a harassment policy will be provided. It felt kind of like a slap in the face. I couldn’t understand where his behavior towards me was coming from and why she all of a sudden stop speaking to me. Then when I saw what I saw it all kind of falls into place. I don’t know what their motives towards me are.Should I bring this up to HR without them telling me I have no proof one more time?Many thanks.