Well, Father Mulligan taught me about sex when I was a wee lad... Or maybe not.
Truthfully, my parents had little to do with my sex education - all the basic to intermediate information you wanted could be found in freely available books, papers (one paper here features sex a few times a week, dealing with everything from the pill to cheating and the history of abortion), movies and of course, the Net. By the time we did have sex education in school, everyone already knew (even the crazy Christian girl who had a panic attack when a Harekrishna came to visit) about safe sex. The only thing sex ed really taught us was the more detailed parts, such as the size of sperm and egg, brief summary of genetics, common STDs and their cures/effects and what porn really is (this we learned at a health centre a mile away, who also went through the basics of abortion and how people shouldn't feel about sex).
I remember we watched a video in class about how you get pregnant and the narrator, after explaining the sperm meets egg part, mentioned briefly how foetuses are very much like parasites - it's stuck with me for some reason. In our final year we also had a teacher who in response to the weekly half-hour the girls got off to sit down and talk about bullying (gangs and that), would sit us boys down and talk about sex and the importance of being safe.
Yeah, that about does it. Sex is common and a natural urge to have... saying that it is wrong is just messing with your head, especially if you're impressionable. If I ever have kids, I won't care if they screw around as teenagers, as long as they are safe, do it willingly, and can look at themselves in the mirror afterwards without feeling bad - unlike klebold who needs to get his head out of his a**.