Some people would be offended by graphic displays of sex and nudity - although if any of them are stupid enough to download a porn game, they deserve what they get.This hasn't ever effected me, but I never know what to expect from a game when they say 'don't play if you're easily offended'. Sometimes I play through the entire game and literally can't tell what they could be referring to. Other times slurs are being dropped left-right-and-centre.
Where you get that message in a porn game, this is usually why: it's to forestall any Moral Majority lunatics who are going to download it with the deliberate intention of being offended and trying to get it banned.