Teens in the over sexed world

So we all know how oversexed the world is, it is everywhere we look and in everything we listen to. It's not like we can hide billboards of half naked people or turn the tv off every time a victorias secret commercial comes on. (well I guess we could but that is very unrealistic)Our kids are exposed to so many things at school and also at friends homes. We can't isolate them from the world~ so what do we do to keep our kids from doing something they might regret?