One of the problems with lewd conversations and sexual jokes is that they can impact people in the workplace, even those who were not part of the conversations initially. They can create a hostile work atmosphere and cause division in the staff, potentially holding some workers back.
For example, one woman worked in an office with a significant number of men, and her boss had a habit of using email to send the rest of the men pictures of models in bikinis. He didn't want to offend her, so he didn't include her.
While he probably thought he was doing this to keep from creating a hostile work environment, the problem was that the email chains would often swing back around to work topics. The men would all have these long conversations about their projects, but the one woman on their team was cut out of those discussions.
Moreover, when the team was doing a conference call, he'd warn the rest of the group to watch their language if she was part of the call. Again, he may have had good intentions, but it had a direct impact on the way they looked at her. Now, they didn't think of her as part of the work team, but as some sort of adversary, a impediment to their conversations and projects.
This shows how sexual topics can make a workplace hostile for some workers, even if nothing was done at their expense or even done intentionally. It can still cause significant problems and the conduct may be very inappropriate for the office. If this has happened to you, and if your career has been compromised, it's important to know what constitutes a hostile work environment and what legal options you have.
Source: Forbes, "Sexual Jokes And Lewd Conversations In The Workplace: Where's The Line?," Emily Heist Moss, accessed Jan. 13, 2017