If your Kids are watching this movie, they are plenty old enough to not have a lecture about it afterwards.
Don't try to pluck messages and morals out of movies, which aren't really there. Movies are a form of creative entertainment, if you talk to your kids about every single inappropriate detail they will not be able to grow up and mature properly, though I do belive there should be some limits, awkward conversations aren't going to teach your children anything.
I think this is a great movie, as I am a great Kevin Smith fan. But I will agree, that is movie is very sexually explicit. I would never let a child see this, and I would be iffy with teens. Teens (believe it or not) actually already know most of the sexual references in this movie from their peers. But this movie revolves around it, and might even cross a border.