To be an unlawful "hostile work environment" based on sex the sexual harassment in the workplace must be severe or pervasive.  The following is an example from an actual case, EEOC v. Central Wholesalers, where a federal appeals court, the United States Court of Appeals for the Fourth Circuit, described evidence that would demonstrate severe or pervasive sexual harassment in the workplace and therefore a hostile work environment based on sex:

We conclude that a reasonable jury could find that the gender-based harassment was objectively severe or pervasive. The evidence shows that Mike, Tony, and Green all regularly referred to women as b***hes. Moreover, DaBay called Medley a b***h a number of times during the November 10 incident. In addition, Mike - whose cubicle was right next to Medley's - had a Playboy calendar on his desk, kept Playboy magazines in his cubicle, hung a Playboy poster on his wall, watched pornography on his computer in Medley's presence, used a pornographic screensaver depicting partially naked women, and placed the screwdriver in the Halloween decoration in a sexual manner more than once.